N = int(input())

As = [[0 for _ in range(N)] for _ in range(N)]

for i in range(N):
    l = list(map(str, input().split()))
    for j in range(N):
        As[j][i] = l[j]

result = -1
for i in range(N):
    if all(x == 'nyanpass' or x == '-' for x in list(As[i])):
        if result == -1:
            result = i + 1
        else:
            result = -1
            break
print(result)