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

l = [list(x) for x in zip(*l)]

for i in range(n):
    l[i].pop(i)

l2 = [list(set(i)) for i in l]    

ans = []
for i in range(n):
    if l2[i] == ['nyanpass']:
        ans.append(i+1)

if len(ans) >= 2 or len(ans) == 0:
    print(-1)
else:
    print(*ans)