def main():
    N = int(input())
    B = [input().split() for i in range(N)]
    *A, = zip(*B)
    x = []
    for a in range(N):
        if A[a].count('nyanpass') == N-1:
            x.append(a+1)
    if len(x) != 1:
        print(-1)
    else:
        print(*x)


if __name__ == '__main__':
    main()