# -*- coding:utf-8 -*-
if __name__ == '__main__':
    n = int(input())
    ann = [input().split() for y in range(n)]
    ans = -1
    for i, an in enumerate(zip(*ann), start=1):
        if an.count('-') != 1:
            continue
        if all(map(lambda a: a in ('-', 'nyanpass'), an)):
            if ans > 0:
                ans = -1
                break
            else:
                ans = i
    print(ans)