import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

import numpy as np

N = int(readline())
A = np.array(read().decode().split()).reshape(N,N)

x = (A == 'nyanpass').sum(axis = 0)
cand = np.where(x == N - 1)[0] + 1

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