Buggy python submission (verdict: Time Limit Exceeded):
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)


Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Runtime Error):
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
opo = [1 for i in range(n)]
cl = opo
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = opo

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)


Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Time Limit Exceeded):
import collections as cl,sys
input = sys.stdin.readline
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = cl.deque()
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)


Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Time Limit Exceeded):
import collections as cl,sys
input = sys.stdin.readline
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)


Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Runtime Error):
n = int(input())
a = list(map(input().split()))

Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Time Limit Exceeded):
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-2 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    de.append([k[-1],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if sum(ppp) == -n:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif ppp[kkk[0]] != -1 and on[kkk[0]][ppp[kkk[0]]] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != -1 and ppp[kkk[0]] != -1 and on[kkk[1]][ppp[kkk[1]]] == kkk[0] and on[kkk[0]][ppp[kkk[0]]] == kkk[1]:
            de.append([on[kkk[1]][ppp[kkk[1]]],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][ppp[kkk[1]]],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][ppp[kkk[0]]],kkk[0]])


print(co)


Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Time Limit Exceeded):
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-2 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    de.append([k[-1],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if sum(ppp) == -n:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif ppp[kkk[0]] != -1 and on[kkk[0]][ppp[kkk[0]]] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != -1 and ppp[kkk[0]] != -1 and on[kkk[1]][ppp[kkk[1]]] == kkk[0] and on[kkk[0]][ppp[kkk[0]]] == kkk[1]:
            de.append([on[kkk[1]][ppp[kkk[1]]],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][ppp[kkk[1]]],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][ppp[kkk[0]]],kkk[0]])


print(co)


Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Time Limit Exceeded):
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)


Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Time Limit Exceeded):
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)


Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Time Limit Exceeded):
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif len(on[kkk[0]]) != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        if len(on[kkk[1]]) != 0 and len(on[kkk[0]]) != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)




Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Time Limit Exceeded):
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif len(on[kkk[0]]) != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        if len(on[kkk[1]]) != 0 and len(on[kkk[0]]) != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)




Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Time Limit Exceeded):



import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
wh = [[-1 for j in range(n)] for i in range(n)]
de = cl.deque()
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]

while de:

    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif len(on[kkk[0]]) != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        if len(on[kkk[1]]) != 0 and len(on[kkk[0]]) != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)


Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Time Limit Exceeded):



import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def m(): #複数文字
    return map(int,input().split())
def onem(): #Nとかの取得
    return int(input())
def s(x): #圧縮
    a = []
    aa = x[0]
    su = 1
    for i in range(len(x)-1):
        if aa != x[i+1]:
            a.append([aa,su])
            aa = x[i+1]
            su = 1
        else:
            su += 1
    a.append([aa,su])
    return a
def jo(x): #listをスペースごとに分ける
    return " ".join(map(str,x))
def max2(x): #他のときもどうように作成可能
    return max(map(max,x))
def In(x,a): #aがリスト(sorted)
    k = bs.bisect_left(a,x)
    if k != len(a) and a[k] ==  x:
        return k
    else:
        return False

n = onem()

on = []
wh = [[-1 for j in range(n)] for i in range(n)]
de = cl.deque()
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]

while de:

    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif len(on[kkk[0]]) != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        if len(on[kkk[1]]) != 0 and len(on[kkk[0]]) != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)















Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Runtime Error):
import collections as cl
mod = 10**9+7

def l(): #intのlist
    return list(map(int,input().split()))
def m(): #複数文字
    return map(int,input().split())
def onem(): #Nとかの取得
    return int(input())
def s(x): #圧縮
    a = []
    aa = x[0]
    su = 1
    for i in range(len(x)-1):
        if aa != x[i+1]:
            a.append([aa,su])
            aa = x[i+1]
            su = 1
        else:
            su += 1
    a.append([aa,su])
    return a
def jo(x): #listをスペースごとに分ける
    return " ".join(map(str,x))
def max2(x): #他のときもどうように作成可能
    return max(map(max,x))
def In(x,a): #aがリスト(sorted)
    k = bs.bisect_left(a,x)
    if k != len(a) and a[k] ==  x:
        return k
    else:
        return False

def Topo_sort(x,y):
    co = cl.Counter(n for m in x.values() for n in m)
    S = cl.deque([i for i in range(y) if co[i] == 0])
    while S:
        n = S.popleft()
        yield n
        for i in x[n]:
            co[i] -= 1
            if co[i] <= 0:
                S.append(i)
    ```
    if sum(co.values()) != 0:
        print(1)
        exit()
    else:
        print(0)
        exit()
    ```
    #閉路検出(1が存在,0が存在しない)
# g = cl.dafaultdict(set)に有向グラフを作成し(g[~] != ~ ,yはノード数) リストが帰ってくる





























Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Time Limit Exceeded):
import sys,collections as cl,bisect as bs,copy
sys.setrecursionlimit(100000)
mod = 10**9+7
Max = sys.maxsize
def l(): #intのlist
    return list(map(int,input().split()))
def m(): #複数文字
    return map(int,input().split())
def onem(): #Nとかの取得
    return int(input())
def s(x): #圧縮
    a = []
    aa = x[0]
    su = 1
    for i in range(len(x)-1):
        if aa != x[i+1]:
            a.append([aa,su])
            aa = x[i+1]
            su = 1
        else:
            su += 1
    a.append([aa,su])
    return a
def jo(x): #listをスペースごとに分ける
    return " ".join(map(str,x))
def max2(x): #他のときもどうように作成可能
    return max(map(max,x))
def In(x,a): #aがリスト(sorted)
    k = bs.bisect_left(a,x)
    if k != len(a) and a[k] ==  x:
        return k
    else:
        return False

n = onem()

on = []
wh = [[-1 for j in range(n)] for i in range(n)]
de = cl.deque()
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]

while de:

    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif len(on[kkk[0]]) != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        if len(on[kkk[1]]) != 0 and len(on[kkk[0]]) != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)


Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Time Limit Exceeded):
import sys,collections as cl,bisect as bs,copy
sys.setrecursionlimit(100000)
mod = 10**9+7
Max = sys.maxsize
def l(): #intのlist
    return list(map(int,input().split()))
def m(): #複数文字
    return map(int,input().split())
def onem(): #Nとかの取得
    return int(input())
def s(x): #圧縮
    a = []
    aa = x[0]
    su = 1
    for i in range(len(x)-1):
        if aa != x[i+1]:
            a.append([aa,su])
            aa = x[i+1]
            su = 1
        else:
            su += 1
    a.append([aa,su])
    return a
def jo(x): #listをスペースごとに分ける
    return " ".join(map(str,x))
def max2(x): #他のときもどうように作成可能
    return max(map(max,x))
def In(x,a): #aがリスト(sorted)
    k = bs.bisect_left(a,x)
    if k != len(a) and a[k] ==  x:
        return k
    else:
        return False

n = onem()

on = []
wh = [[-1 for j in range(n)] for i in range(n)]
de = cl.deque()
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]

while de:

    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif len(on[kkk[0]]) != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        if len(on[kkk[1]]) != 0 and len(on[kkk[0]]) != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Runtime Error):
import sys,collections as cl,bisect as bs,copy
sys.setrecursionlimit(100000)
mod = 10**9+7
Max = sys.maxsize
def l(): #intのlist
    return list(map(int,input().split()))
def m(): #複数文字
    return map(int,input().split())
def onem(): #Nとかの取得
    return int(input())
def s(x): #圧縮
    a = []
    aa = x[0]
    su = 1
    for i in range(len(x)-1):
        if aa != x[i+1]:
            a.append([aa,su])
            aa = x[i+1]
            su = 1
        else:
            su += 1
    a.append([aa,su])
    return a
def jo(x): #listをスペースごとに分ける
    return " ".join(map(str,x))
def max2(x): #他のときもどうように作成可能
    return max(map(max,x))
def In(x,a): #aがリスト(sorted)
    k = bs.bisect_left(a,x)
    if k != len(a) and a[k] ==  x:
        return k
    else:
        return False

n = onem()

on = []
wh = [[-1 for j in range(n)] for i in range(n)]
de = cl.deque()
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]

while de:

    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        if len(on[kkk[1]]) != 0 and len(on[kkk[0]]) != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)


Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Runtime Error):
import sys,collections as cl,bisect as bs,copy
sys.setrecursionlimit(100000)
mod = 10**9+7
Max = sys.maxsize
def l(): #intのlist
    return list(map(int,input().split()))
def m(): #複数文字
    return map(int,input().split())
def onem(): #Nとかの取得
    return int(input())
def s(x): #圧縮
    a = []
    aa = x[0]
    su = 1
    for i in range(len(x)-1):
        if aa != x[i+1]:
            a.append([aa,su])
            aa = x[i+1]
            su = 1
        else:
            su += 1
    a.append([aa,su])
    return a
def jo(x): #listをスペースごとに分ける
    return " ".join(map(str,x))
def max2(x): #他のときもどうように作成可能
    return max(map(max,x))
def In(x,a): #aがリスト(sorted)
    k = bs.bisect_left(a,x)
    if k != len(a) and a[k] ==  x:
        return k
    else:
        return False

n = onem()

on = []
wh = [[-1 for j in range(n)] for i in range(n)]
de = cl.deque()
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]

while de:

    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        if on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        elif len(on[kkk[1]]) != 0:
            de.append([on[kkk[1]][0],kkk[1]])
        elif len(on[kkk[0]]) != 0:
            de.append([on[kkk[0]][0],kkk[0]])


print(co)


Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Runtime Error):
import sys,collections as cl,bisect as bs,copy
sys.setrecursionlimit(100000)
mod = 10**9+7
Max = sys.maxsize
def l(): #intのlist
    return list(map(int,input().split()))
def m(): #複数文字
    return map(int,input().split())
def onem(): #Nとかの取得
    return int(input())
def s(x): #圧縮
    a = []
    aa = x[0]
    su = 1
    for i in range(len(x)-1):
        if aa != x[i+1]:
            a.append([aa,su])
            aa = x[i+1]
            su = 1
        else:
            su += 1
    a.append([aa,su])
    return a
def jo(x): #listをスペースごとに分ける
    return " ".join(map(str,x))
def max2(x): #他のときもどうように作成可能
    return max(map(max,x))
def In(x,a): #aがリスト(sorted)
    k = bs.bisect_left(a,x)
    if k != len(a) and a[k] ==  x:
        return k
    else:
        return False

n = onem()

on = []
wh = [[-1 for j in range(n)] for i in range(n)]
de = cl.deque()
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
cl = [1 for i in range(n)]

while de:

    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = [1 for i in range(n)]

    elif on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        if len(on[kkk[1]]) != 0:
            de.append([on[kkk[1]][0],kkk[1]])
        if len(on[kkk[0]]) != 0:
            de.append([on[kkk[0]][0],kkk[0]])


print(co)


Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Runtime Error):
import sys,collections as cl,bisect as bs,copy
sys.setrecursionlimit(100000)
mod = 10**9+7
Max = sys.maxsize
def l(): #intのlist
    return list(map(int,input().split()))
def m(): #複数文字
    return map(int,input().split())
def onem(): #Nとかの取得
    return int(input())
def s(x): #圧縮
    a = []
    aa = x[0]
    su = 1
    for i in range(len(x)-1):
        if aa != x[i+1]:
            a.append([aa,su])
            aa = x[i+1]
            su = 1
        else:
            su += 1
    a.append([aa,su])
    return a
def jo(x): #listをスペースごとに分ける
    return " ".join(map(str,x))
def max2(x): #他のときもどうように作成可能
    return max(map(max,x))
def In(x,a): #aがリスト(sorted)
    k = bs.bisect_left(a,x)
    if k != len(a) and a[k] ==  x:
        return k
    else:
        return False

n = onem()

on = []
wh = [[-1 for j in range(n)] for i in range(n)]
de = cl.deque()
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    de.append([k[-1],i])
    on.append(cl.deque(k))


co = 0
ddd = []
while True:
    ddd = []
    co += 1
    cl = [1 for i in range(n)]
    
    while de:
        kkk = de.popleft()
        if on[kkk[0]][-1] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
            cl[kkk[0]] = 0
            cl[kkk[1]] = 0
            on[kkk[0]].pop()
            on[kkk[1]].pop()
            if len(on[kkk[1]]) != 0:
                ddd.append([on[kkk[1]][-1],kkk[1]])
            if len(on[kkk[0]]) != 0:
                ddd.append([on[kkk[0]][-1],kkk[0]])
    de = ddd[:]
    
    if sum(cl) == n:
        co = -1
        break
    elif len(de) == 0:
        break

print(co)





















Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)

Buggy python submission (verdict: Runtime Error):
import sys,collections as cl,bisect as bs,copy
sys.setrecursionlimit(100000)
mod = 10**9+7
Max = sys.maxsize
def l(): #intのlist
    return list(map(int,input().split()))
def m(): #複数文字
    return map(int,input().split())
def onem(): #Nとかの取得
    return int(input())
def s(x): #圧縮
    a = []
    aa = x[0]
    su = 1
    for i in range(len(x)-1):
        if aa != x[i+1]:
            a.append([aa,su])
            aa = x[i+1]
            su = 1
        else:
            su += 1
    a.append([aa,su])
    return a
def jo(x): #listをスペースごとに分ける
    return " ".join(map(str,x))
def max2(x): #他のときもどうように作成可能
    return max(map(max,x))
def In(x,a): #aがリスト(sorted)
    k = bs.bisect_left(a,x)
    if k != len(a) and a[k] ==  x:
        return k
    else:
        return False

n = onem()

on = []
wh = [[-1 for j in range(n)] for i in range(n)]
de = cl.deque()
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 0
ddd = cl.deque()
while True:
    ddd.clear()
    co += 1
    cl = [1 for i in range(n)]
    
    while de:
        kkk = de.popleft()
        if on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
            cl[kkk[0]] = 0
            cl[kkk[1]] = 0
            on[kkk[0]].popleft()
            on[kkk[1]].popleft()
            if len(on[kkk[1]]) != 0:
                ddd.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                ddd.append([on[kkk[0]][0],kkk[0]])
    de = copy.deepcopy(ddd)
    
    if sum(cl) == n:
        co = -1
        break
    elif len(de) == 0:
        break

print(co)





















Fixed submission:
import collections as cl
def l(): #intのlist
    return list(map(int,input().split()))
def onem(): #Nとかの取得
    return int(input())
n = onem()

on = []
de = cl.deque()
ppp = [n-1 for i in range(n)]
for i in range(n):
    k = l()
    for j in range(n-1):
        k[j] -= 1
    k.reverse()
    de.append([k[0],i])
    on.append(cl.deque(k))


co = 1
ddd = cl.deque()
de.append([-1,-1])
ppppp = [1 for i in range(n)]
cl = ppppp[:]
while de:
    kkk = de.popleft()
    if kkk[0] == -1 and kkk[1] == -1:
        if sum(cl) == n:
            co = -1
            break
        if len(de) == 0:
            break
        de.append([-1,-1])
        co += 1
        cl = ppppp[:]

    elif ppp[kkk[0]] != 0 and on[kkk[0]][0] == kkk[1] and cl[kkk[0]] and cl[kkk[1]]:
        cl[kkk[0]] = 0
        cl[kkk[1]] = 0
        on[kkk[0]].popleft()
        on[kkk[1]].popleft()
        ppp[kkk[0]] -= 1
        ppp[kkk[1]] -= 1
        if ppp[kkk[1]] != 0 != 0 and ppp[kkk[0]] != 0 and on[kkk[1]][0] == kkk[0] and on[kkk[0]][0] == kkk[1]:
            de.append([on[kkk[1]][0],kkk[1]])
        else:
            if len(on[kkk[1]]) != 0:
                de.append([on[kkk[1]][0],kkk[1]])
            if len(on[kkk[0]]) != 0:
                de.append([on[kkk[0]][0],kkk[0]])


print(co)