def main():
    N = int(input())
    A = tuple(tuple(input().split()) for _ in [0] * N)

    num = dict()
    for a in A:
        for i in range(N):
            if a[i] == 'nyanpass' or a[i] == '-':
                num[i] = num.get(i, 0) + 1

    ans = -1
    for key, val in num.items():
        if val == N:
            if ans > -1:
                ans = -1
                break
            else:
                ans = key + 1
    print(ans)

main()