# -*- coding: utf-8 -*-

n = int(input())
a = [["" for i in range(n)] for j in range(n)]
yougisha = []

for i in range(n):
    temp = input().split()
    for j in range(n):
        a[j][i] = temp[j]
for j in range(n):
    a[j] = set(a[j])
for j in range(n):
    if a[j] == {"nyanpass", "-"}:
        yougisha.append(j+1)

if len(yougisha) == 1:
    print(yougisha[0])
else:
    print(-1)