Buggy python submission (verdict: Time Limit Exceeded):
def resolve():
    n = int(input())
    am = []

    from collections import deque

    for i in range(n):
        am.append(deque(list(map(lambda x: int(x) - 1, input().split()))))

    cnt = n * (n - 1) // 2

    day = 0
    while cnt > 0:
        day += 1
        match = 0
        done = {}
        for i in range(n):
            if i in done:
                continue
            if len(am[i]) == 0:
                continue
            j = am[i][0]
            if j < i:
                continue
            if j not in done and am[j][0] == i:
                am[i].popleft()
                am[j].popleft()
                done[i] = 1
                done[j] = 1
                match += 1

        if match == 0:
            print(-1)
            return
        else:
            cnt -= match

    print(day)
    
resolve()

Fixed submission:
def resolve():
    n = int(input())
    a = []

    for i in range(n):
        row = list(map(lambda x: int(x) - 1, input().split()))
        row.reverse()
        a.append(row)

    q = set()

    def check(i):
        if len(a[i]) == 0:
            return
        j = a[i][-1]
        if i == a[j][-1]:
            p = (i, j) if i < j else (j, i)
            q.add(p)

    for i in range(n):
        check(i)

    day = 0
    while len(q) > 0:
        day += 1
        prev_q, q = q, set()

        for p in prev_q:
            (i, j) = p
            a[i].pop()
            a[j].pop()

        for p in prev_q:
            (i, j) = p
            check(i)
            check(j)

    for i in range(n):
        if len(a[i]) != 0:
            print(-1)
            return
    print(day)
    
resolve()

Buggy python submission (verdict: Time Limit Exceeded):
def resolve():
    n = int(input())
    am = []
 
    from collections import deque
 
    for i in range(n):
        am.append(deque(list(map(lambda x: int(x) - 1, input().split()))))
 
    cnt = n * (n - 1) // 2
 
    day = 0
    while cnt > 0:
        day += 1
        match = 0
        done = {}
        for i in range(n):
            if i in done:
                continue
            if len(am[i]) == 0:
                continue
            j = am[i][0]
            if j not in done and am[j][0] == i:
                am[i].popleft()
                am[j].popleft()
                done[i] = 1
                done[j] = 1
                match += 1
 
        if match == 0:
            print(-1)
            return
        else:
            cnt -= match
 
    print(day)
    
resolve()

Fixed submission:
def resolve():
    n = int(input())
    a = []

    for i in range(n):
        row = list(map(lambda x: int(x) - 1, input().split()))
        row.reverse()
        a.append(row)

    q = set()

    def check(i):
        if len(a[i]) == 0:
            return
        j = a[i][-1]
        if i == a[j][-1]:
            p = (i, j) if i < j else (j, i)
            q.add(p)

    for i in range(n):
        check(i)

    day = 0
    while len(q) > 0:
        day += 1
        prev_q, q = q, set()

        for p in prev_q:
            (i, j) = p
            a[i].pop()
            a[j].pop()

        for p in prev_q:
            (i, j) = p
            check(i)
            check(j)

    for i in range(n):
        if len(a[i]) != 0:
            print(-1)
            return
    print(day)
    
resolve()

Buggy python submission (verdict: Time Limit Exceeded):
def resolve():
    n = int(input())
    am = []

    from collections import deque

    for i in range(n):
        am.append(deque(list(map(lambda x: int(x) - 1, input().split()))))

    cnt = n * (n - 1) // 2

    day = 0
    while cnt > 0:
        day += 1
        match = 0
        blocked = {}
        done = {}
        for i in range(n):
            if i in done:
                continue
            if len(am[i]) == 0:
                continue
            j = am[i][0]
            if j in blocked:
                continue
            if j not in done and am[j][0] == i:
                am[i].popleft()
                am[j].popleft()
                done[i] = 1
                done[j] = 1
                match += 1
            else:
                blocked[i] = 1

            if match == cnt:
                break

        if match == 0:
            print(-1)
            return
        else:
            cnt -= match

    print(day)
    
resolve()

Fixed submission:
def resolve():
    n = int(input())
    a = []

    for i in range(n):
        row = list(map(lambda x: int(x) - 1, input().split()))
        row.reverse()
        a.append(row)

    q = set()

    def check(i):
        if len(a[i]) == 0:
            return
        j = a[i][-1]
        if i == a[j][-1]:
            p = (i, j) if i < j else (j, i)
            q.add(p)

    for i in range(n):
        check(i)

    day = 0
    while len(q) > 0:
        day += 1
        prev_q, q = q, set()

        for p in prev_q:
            (i, j) = p
            a[i].pop()
            a[j].pop()

        for p in prev_q:
            (i, j) = p
            check(i)
            check(j)

    for i in range(n):
        if len(a[i]) != 0:
            print(-1)
            return
    print(day)
    
resolve()

Buggy python submission (verdict: Time Limit Exceeded):
def resolve():
    n = int(input())
    am = []

    from collections import deque

    for i in range(n):
        am.append(deque(list(map(lambda x: int(x) - 1, input().split()))))

    cnt = n * (n - 1) // 2

    day = 0
    while cnt > 0:
        day += 1
        match = 0
        done = {}
        for i in range(n):
            if i in done:
                continue
            if len(am[i]) == 0:
                continue
            j = am[i][0]
            if j not in done and am[j][0] == i:
                am[i].popleft()
                am[j].popleft()
                done[i] = 1
                done[j] = 1
                match += 1

        if match == 0:
            print(-1)
            return
        else:
            cnt -= match

    print(day)
    
resolve()

Fixed submission:
def resolve():
    n = int(input())
    a = []

    for i in range(n):
        row = list(map(lambda x: int(x) - 1, input().split()))
        row.reverse()
        a.append(row)

    q = set()

    def check(i):
        if len(a[i]) == 0:
            return
        j = a[i][-1]
        if i == a[j][-1]:
            p = (i, j) if i < j else (j, i)
            q.add(p)

    for i in range(n):
        check(i)

    day = 0
    while len(q) > 0:
        day += 1
        prev_q, q = q, set()

        for p in prev_q:
            (i, j) = p
            a[i].pop()
            a[j].pop()

        for p in prev_q:
            (i, j) = p
            check(i)
            check(j)

    for i in range(n):
        if len(a[i]) != 0:
            print(-1)
            return
    print(day)
    
resolve()