use std::io::*;

fn main() {
    let mut s: String = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let n: usize = itr.next().unwrap().parse().unwrap();
    let grid: Vec<Vec<&str>> = (0..n)
        .map(|_| (0..n).map(|_| itr.next().unwrap()).collect())
        .collect();

    let mut ans = 0;
    for j in 0..n {
        let mut ok = true;
        for i in 0..n {
            if i == j {
                continue;
            }
            if grid[i][j] != "nyanpass" {
                ok = false;
            }
        }
        if ok {
            if ans != 0 {
                println!("-1",);
                return;
            } else {
                ans = j + 1;
            }
        }
    }
    if ans == 0 {
        println!("-1",)
    } else {
        println!("{}", ans)
    }
}