N = int(input())
L1 = [input().split() for _ in range(N)]
L2 = [[L1[j][i] for j in range(N)] for i in range(N)]

L3 = []
for i, s in enumerate(L2):
    L4 = sorted(set(s))
    if len(L4) == 2 and L4 == ['-', 'nyanpass']:
        L3 += [i+1]

print([-1, *L3][len(L3) == 1])