def main():
    N = int(input())

    number = -1
    gss = [
        input().split()
        for _ in range(N)
    ]

    for gs in gss:
        for i, g in enumerate(gs, 1):
            if g != "nyanpass":
                continue
            if number == -1:
                number = i
            elif number != i:
                print(-1)
                return

    print(number)

if __name__ == '__main__':
    main()