Buggy python submission (verdict: Time Limit Exceeded):
import sys
from collections import deque

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))

N = ir()
A = [deque([(i, x) for x in lr()]) for i in range(1, N+1)]
day = 0
candidate = set()
match = 0
for i in range(N):
    c = A[i].popleft()
    candidate.add(c)

while candidate:
    day += 1
    used = set()
    next = set()
    rmv = set()
    for a, b in candidate:
        if a in used or b in used:
            continue
        if (b, a) in candidate:
            rmv.add((a, b))
            rmv.add((b, a))
            match += 1
            if A[a-1]:
                x = A[a-1].popleft()
                next.add(x)
            if A[b-1]:
                y = A[b-1].popleft()
                next.add(y)
            used.add(a)
            used.add(b)
    candidate -= rmv
    if match == N * (N-1) // 2:
        break
    candidate |= next
    if not used:
        print(-1); exit()

print(day)
# 10


Fixed submission:
import sys
import copy
from collections import deque

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))

N = ir()
A = [deque(lr()) for _ in range(N)]

match = 0
candidate = []
used = set()
for i in range(N):    
    bool = False
    if len(A[i]) == 0:
        continue
    op = A[i][0] - 1
    if op in used or i in used:
        continue
    if A[op][0]-1 == i:
        used.add(i)
        used.add(op)
        candidate.extend([i, op])
        match += 1
        bool = True
        A[i].popleft()
        A[op].popleft()
answer = 1

while True:
    used = set()
    bool = False
    c = []
    for i in candidate:
        if len(A[i]) == 0:
            continue
        op = A[i][0] - 1
        if op in used or i in used:
            continue
        if A[op][0]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            c.extend([i, op])
            bool = True
            A[i].popleft()
            A[op].popleft()
    
    answer += 1
    candidate = c
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
from collections import deque

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))

N = ir()
A = [deque([(i, x) for x in lr()]) for i in range(1, N+1)]
day = 0
candidate = set()
match = 0
for i in range(N):
    c = A[i].popleft()
    candidate.add(c)

while candidate:
    day += 1
    used = set()
    next = set()
    rmv = set()
    for a, b in candidate:
        if a in used or b in used:
            continue
        if (b, a) in candidate:
            rmv.add((a, b))
            rmv.add((b, a))
            match += 1
            if A[a-1]:
                x = A[a-1].popleft()
                next.add(x)
            if A[b-1]:
                y = A[b-1].popleft()
                next.add(y)
            used.add(a)
            used.add(b)
    for r in rmv:
        candidate.remove(r)
    if match == N * (N-1) // 2:
        break
    candidate |= next
    if not used:
        print(-1); exit()

print(day)
# 10

Fixed submission:
import sys
import copy
from collections import deque

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))

N = ir()
A = [deque(lr()) for _ in range(N)]

match = 0
candidate = []
used = set()
for i in range(N):    
    bool = False
    if len(A[i]) == 0:
        continue
    op = A[i][0] - 1
    if op in used or i in used:
        continue
    if A[op][0]-1 == i:
        used.add(i)
        used.add(op)
        candidate.extend([i, op])
        match += 1
        bool = True
        A[i].popleft()
        A[op].popleft()
answer = 1

while True:
    used = set()
    bool = False
    c = []
    for i in candidate:
        if len(A[i]) == 0:
            continue
        op = A[i][0] - 1
        if op in used or i in used:
            continue
        if A[op][0]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            c.extend([i, op])
            bool = True
            A[i].popleft()
            A[op].popleft()
    
    answer += 1
    candidate = c
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)

Buggy python submission (verdict: Runtime Error):
import sys
import copy
from collections import deque

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))

N = ir()
A = [deque(lr()) for _ in range(N)]

answer = 0
match = 0

candidate = list(range(N))
while True:
    used = set()
    bool = False
    c = []
    for i in candidate:
        op = A[i][0] - 1
        if op in used or i in used:
            continue
        if A[op][0]-1 == i:
            used.add(i)
            used.add(op)
            match += 1            
            bool = True
            A[i].popleft()
            A[op].popleft()
            if A[i]: c.append(i)
            if A[op]: c.append(op)

    answer += 1
    candidate = c
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)


Fixed submission:
import sys
import copy
from collections import deque

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))

N = ir()
A = [deque(lr()) for _ in range(N)]

match = 0
candidate = []
used = set()
for i in range(N):    
    bool = False
    if len(A[i]) == 0:
        continue
    op = A[i][0] - 1
    if op in used or i in used:
        continue
    if A[op][0]-1 == i:
        used.add(i)
        used.add(op)
        candidate.extend([i, op])
        match += 1
        bool = True
        A[i].popleft()
        A[op].popleft()
answer = 1

while True:
    used = set()
    bool = False
    c = []
    for i in candidate:
        if len(A[i]) == 0:
            continue
        op = A[i][0] - 1
        if op in used or i in used:
            continue
        if A[op][0]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            c.extend([i, op])
            bool = True
            A[i].popleft()
            A[op].popleft()
    
    answer += 1
    candidate = c
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
from collections import deque

stdin = sys.stdin

ri = lambda: int(rs())
rl = lambda: list(map(int, stdin.readline().split())) # applies to numbers only
rs = lambda: stdin.readline().rstrip()  # ignore trailing spaces

N = ri()
A = [deque(rl()) for _ in range(N)]
answer = 0
match = 0
while True:
    used = set()
    bool = False
    for i in range(N):
        if len(A[i]) == 0:
            continue
        op = A[i][0] - 1
        if op in used or i in used:
            continue
        if A[op][0]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            bool = True
            A[i].popleft()
            A[op].popleft()
    
    answer += 1
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)


Fixed submission:
import sys
import copy
from collections import deque

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))

N = ir()
A = [deque(lr()) for _ in range(N)]

match = 0
candidate = []
used = set()
for i in range(N):    
    bool = False
    if len(A[i]) == 0:
        continue
    op = A[i][0] - 1
    if op in used or i in used:
        continue
    if A[op][0]-1 == i:
        used.add(i)
        used.add(op)
        candidate.extend([i, op])
        match += 1
        bool = True
        A[i].popleft()
        A[op].popleft()
answer = 1

while True:
    used = set()
    bool = False
    c = []
    for i in candidate:
        if len(A[i]) == 0:
            continue
        op = A[i][0] - 1
        if op in used or i in used:
            continue
        if A[op][0]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            c.extend([i, op])
            bool = True
            A[i].popleft()
            A[op].popleft()
    
    answer += 1
    candidate = c
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
from collections import deque

stdin = sys.stdin

ri = lambda: int(rs())
rl = lambda: list(map(int, stdin.readline().split())) # applies to numbers only
rs = lambda: stdin.readline().rstrip()  # ignore trailing spaces

N = ri()
A = [deque(rl()) for _ in range(N)]
answer = 0
match = 0
while True:
    used = set()
    bool = False
    for i in range(N):
        if len(A[i]) == 0:
            continue
        op = A[i][0] - 1
        if op in used or i in used:
            continue
        if A[op][0]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            bool = True
            A[i].popleft()
            A[op].popleft()
    
    answer += 1
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)


Fixed submission:
import sys
import copy
from collections import deque

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))

N = ir()
A = [deque(lr()) for _ in range(N)]

match = 0
candidate = []
used = set()
for i in range(N):    
    bool = False
    if len(A[i]) == 0:
        continue
    op = A[i][0] - 1
    if op in used or i in used:
        continue
    if A[op][0]-1 == i:
        used.add(i)
        used.add(op)
        candidate.extend([i, op])
        match += 1
        bool = True
        A[i].popleft()
        A[op].popleft()
answer = 1

while True:
    used = set()
    bool = False
    c = []
    for i in candidate:
        if len(A[i]) == 0:
            continue
        op = A[i][0] - 1
        if op in used or i in used:
            continue
        if A[op][0]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            c.extend([i, op])
            bool = True
            A[i].popleft()
            A[op].popleft()
    
    answer += 1
    candidate = c
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
from collections import deque

stdin = sys.stdin

ri = lambda: int(rs())
rl = lambda: list(map(int, stdin.readline().split())) # applies to numbers only
rs = lambda: stdin.readline().rstrip()  # ignore trailing spaces

N = ri()
A = [deque(rl()[::-1]) for _ in range(N)]
answer = 0
match = 0
while True:
    used = set()
    bool = False
    for i in range(N):
        if len(A[i]) == 0:
            continue
        op = A[i][-1] - 1
        if op in used or i in used:
            continue
        if A[op][-1]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            bool = True
            A[i].pop()
            A[op].pop()
    
    answer += 1
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)


Fixed submission:
import sys
import copy
from collections import deque

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))

N = ir()
A = [deque(lr()) for _ in range(N)]

match = 0
candidate = []
used = set()
for i in range(N):    
    bool = False
    if len(A[i]) == 0:
        continue
    op = A[i][0] - 1
    if op in used or i in used:
        continue
    if A[op][0]-1 == i:
        used.add(i)
        used.add(op)
        candidate.extend([i, op])
        match += 1
        bool = True
        A[i].popleft()
        A[op].popleft()
answer = 1

while True:
    used = set()
    bool = False
    c = []
    for i in candidate:
        if len(A[i]) == 0:
            continue
        op = A[i][0] - 1
        if op in used or i in used:
            continue
        if A[op][0]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            c.extend([i, op])
            bool = True
            A[i].popleft()
            A[op].popleft()
    
    answer += 1
    candidate = c
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
#import numpy as np

stdin = sys.stdin

ri = lambda: int(rs())
rl = lambda: list(map(int, stdin.readline().split())) # applies to numbers only
rs = lambda: stdin.readline().rstrip()  # ignore trailing spaces

N = ri()
A = [rl()[::-1] for _ in range(N)]
answer = 0
match = 0
while True:
    used = set()
    bool = False
    for i in range(N):
        if len(A[i]) == 0:
            continue
        op = A[i][-1] - 1
        if op in used or i in used:
            continue
        if op > i and A[op][-1]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            bool = True
            A[i].pop()
            A[op].pop()
    
    answer += 1
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)


Fixed submission:
import sys
import copy
from collections import deque

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))

N = ir()
A = [deque(lr()) for _ in range(N)]

match = 0
candidate = []
used = set()
for i in range(N):    
    bool = False
    if len(A[i]) == 0:
        continue
    op = A[i][0] - 1
    if op in used or i in used:
        continue
    if A[op][0]-1 == i:
        used.add(i)
        used.add(op)
        candidate.extend([i, op])
        match += 1
        bool = True
        A[i].popleft()
        A[op].popleft()
answer = 1

while True:
    used = set()
    bool = False
    c = []
    for i in candidate:
        if len(A[i]) == 0:
            continue
        op = A[i][0] - 1
        if op in used or i in used:
            continue
        if A[op][0]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            c.extend([i, op])
            bool = True
            A[i].popleft()
            A[op].popleft()
    
    answer += 1
    candidate = c
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
#import numpy as np

stdin = sys.stdin

ri = lambda: int(rs())
rl = lambda: list(map(int, stdin.readline().split())) # applies to numbers only
rs = lambda: stdin.readline().rstrip()  # ignore trailing spaces

N = ri()
A = [rl()[::-1] for _ in range(N)]
answer = 0
match = 0
while A:
    used = set()
    bool = False
    for i in range(N):
        if len(A[i]) == 0:
            continue
        op = A[i][-1] - 1
        if op in used or i in used:
            continue
        if op > i and A[op][-1]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            bool = True
            A[i].pop()
            A[op].pop()
    
    answer += 1
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)


Fixed submission:
import sys
import copy
from collections import deque

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))

N = ir()
A = [deque(lr()) for _ in range(N)]

match = 0
candidate = []
used = set()
for i in range(N):    
    bool = False
    if len(A[i]) == 0:
        continue
    op = A[i][0] - 1
    if op in used or i in used:
        continue
    if A[op][0]-1 == i:
        used.add(i)
        used.add(op)
        candidate.extend([i, op])
        match += 1
        bool = True
        A[i].popleft()
        A[op].popleft()
answer = 1

while True:
    used = set()
    bool = False
    c = []
    for i in candidate:
        if len(A[i]) == 0:
            continue
        op = A[i][0] - 1
        if op in used or i in used:
            continue
        if A[op][0]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            c.extend([i, op])
            bool = True
            A[i].popleft()
            A[op].popleft()
    
    answer += 1
    candidate = c
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)

Buggy python submission (verdict: Runtime Error):
import sys
#import numpy as np

stdin = sys.stdin

ri = lambda: int(rs())
rl = lambda: list(map(int, stdin.readline().split())) # applies to numbers only
rs = lambda: stdin.readline().rstrip()  # ignore trailing spaces

N = ri()
A = [rl().reverse() for _ in range(N)]
answer = 0
match = 0
while A:
    bool = False
    for i in range(N):
        op = A[i][-1] - 1
        if op > i and A[op] == i:
            match += 1
            bool = True
            A[i].pop()
            A[op].pop()
    if not bool:
        print(-1)
        exit()
    answer += 1
    if match == N * (N-1) // 2:
        break

print(answer)


Fixed submission:
import sys
import copy
from collections import deque

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))

N = ir()
A = [deque(lr()) for _ in range(N)]

match = 0
candidate = []
used = set()
for i in range(N):    
    bool = False
    if len(A[i]) == 0:
        continue
    op = A[i][0] - 1
    if op in used or i in used:
        continue
    if A[op][0]-1 == i:
        used.add(i)
        used.add(op)
        candidate.extend([i, op])
        match += 1
        bool = True
        A[i].popleft()
        A[op].popleft()
answer = 1

while True:
    used = set()
    bool = False
    c = []
    for i in candidate:
        if len(A[i]) == 0:
            continue
        op = A[i][0] - 1
        if op in used or i in used:
            continue
        if A[op][0]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            c.extend([i, op])
            bool = True
            A[i].popleft()
            A[op].popleft()
    
    answer += 1
    candidate = c
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
#import numpy as np

stdin = sys.stdin

ri = lambda: int(rs())
rl = lambda: list(map(int, stdin.readline().split())) # applies to numbers only
rs = lambda: stdin.readline().rstrip()  # ignore trailing spaces

N = ri()
A = [rl()[::-1] for _ in range(N)]
answer = 0
match = 0
while A:
    used = set()
    bool = False
    for i in range(N):
        if len(A[i]) == 0:
            continue
        op = A[i][-1] - 1
        if op in used or i in used:
            continue
        if op > i and A[op][-1]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            bool = True
            A[i].pop()
            A[op].pop()
    
    answer += 1
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)


Fixed submission:
import sys
import copy
from collections import deque

sr = lambda: sys.stdin.readline().rstrip()
ir = lambda: int(sr())
lr = lambda: list(map(int, sr().split()))

N = ir()
A = [deque(lr()) for _ in range(N)]

match = 0
candidate = []
used = set()
for i in range(N):    
    bool = False
    if len(A[i]) == 0:
        continue
    op = A[i][0] - 1
    if op in used or i in used:
        continue
    if A[op][0]-1 == i:
        used.add(i)
        used.add(op)
        candidate.extend([i, op])
        match += 1
        bool = True
        A[i].popleft()
        A[op].popleft()
answer = 1

while True:
    used = set()
    bool = False
    c = []
    for i in candidate:
        if len(A[i]) == 0:
            continue
        op = A[i][0] - 1
        if op in used or i in used:
            continue
        if A[op][0]-1 == i:
            used.add(i)
            used.add(op)
            match += 1
            c.extend([i, op])
            bool = True
            A[i].popleft()
            A[op].popleft()
    
    answer += 1
    candidate = c
    if match == N * (N-1) // 2:
        break
    if not bool:
        print(-1)
        exit()

print(answer)