N = int(input())
A = [input().split() for _ in range(N)]
cnt = [0 for _ in range(N)]
for i in range(N):
    for j in range(N):
        if A[i][j]=="nyanpass":
            cnt[j] += 1
if cnt.count(N-1)==1:
    print(cnt.index(N-1)+1)
else:
    print(-1)