def enumerate_col(mat, start=0):
    return enumerate(zip(*mat), start=start)

N = int(input())

greeting_table = [
    input().split() for _ in range(N)
]
renchons = [
    i for i, greets in enumerate_col(greeting_table, start=1)
    if all(elem in ('nyanpass', '-') for elem in greets)
]

print(
    renchons[0] if len(renchons) == 1 else -1
)