X = "nyanpass"
N = int(input())
R = []

A = list(map(str, input().split()))
for j in range(N):
    if A[j] == X:
        R.append(j)

A = list(map(str, input().split()))
for j in range(N):
    if j == 0:
        if A[j] == X:
            R.append(j)
    else:
        if A[j] != '-':
            if j in R and A[j] != X:
                R.remove(j)

for i in range(N-2):
    A = list(map(str, input().split()))
    for j in range(N):
        if A[j] != '-':
            if j in R and A[j] != X:
                R.remove(j)       

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