def col_slice(mat, col_num):
    return [row[col_num] for row in mat]

def col_enumerate(mat, start=0):
    for col, _ in enumerate(mat[0]):
        yield start, col_slice(mat, col)
        start += 1

N = int(input())

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

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