use proconio::input;

fn main() {
	input! {
		n: usize,
		a: [[String; n]; n],
	}

    let mut ans = Vec::new();

    for i in 0..n {
        let mut flag = true;

        for j in 0..n {
            if a[j][i] != "nyanpass".to_string() && a[j][i] != "-".to_string() {
                flag = false;
            }
        }

        if flag {
            ans.push(i+1);
        }
    }

    let ans = if ans.len() == 1 {
        ans[0] as isize
    } else {
        -1
    };

	println!("{ans}");
}