n =int(input())
anslist = []

koiwai_list = [input().split(" ") for i in range(n)]
for i in range(n):
    kotolist = [ koiwai_list[j][i] for j in range(n) ]
    if kotolist.count("nyanpass") == n-1:
        anslist.append(i)

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