import numpy as np
import collections

n = int(input())
a = [input().split() for l in range(n)]

arr_a = np.array(a)

renindex = []

for i in range(arr_a.shape[0]):
    for j in range(arr_a.shape[1]):
        if arr_a[i][j] == 'nyanpass':
            renindex.append(j)
            
cl = collections.Counter(renindex)

renkeys = [k for k, v in cl.items() if v == n-1]

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