import numpy as np

n = int(input())

a = np.array([list(input().split()) for _ in range(n)])

bl = a == "nyanpass"
cnt = bl.sum(axis=0)
bl_cnt = cnt == n - 1

if bl_cnt.sum() == 1:
    for i, e in enumerate(bl_cnt, 1):
        if e:
            print(i)

else:
    print(-1)