#!/usr/bin/env python3
n = int(input())
f = []
for i in range(n):
    f += [input().split()]
f = list(map(lambda *xs: xs, *f)) # transpose
ans = []
for i in range(n):
    if f[i].count('nyanpass') == n-1:
        ans += [i]
if len(ans) == 1:
    print(ans[0] + 1)
else:
    print(-1)