N = int(input())

L = [1] * N
ans = 0

for _ in range(N):
    A = input().split()
    for i in range(N):
        L[i] *= (A[i]=='nyanpass' or A[i]=='-')

if L.count(1) == 1:
    print(L.index(1)+1)
else:
    print(-1)