rentyon = "nyanpass"
N = int(input())
Amat = [ input().split() for i in range(N) ]
res = [True]*N
for row in Amat:
    for i, a in enumerate(row):
        if rentyon != a and a != "-":
            res[i] = False

if sum(res) == 1:
    for i, r in enumerate(res, start=1):
        if r:
            print(i)
else:
    print(-1)