#!/usr/bin/env python3
#fileencoding: utf-8

N = int(input())
mat = [[j for j in input().strip().split(" ")] for i in range(N)]

ren = -1
for i,v in enumerate(zip(*mat)):
    tmp = list(set([j for j in v if j != "-"]))
    if len(tmp) == 1 and tmp[0] == "nyanpass":
        if ren == -1:
            ren = i + 1
        else:
            ren = -1
            break
print(ren)