use proconio::input;
fn main(){
    input!{
        n:usize,
    }
    let mut a=[1;100];
    let mut ans=n;
    for i in (0..n){
        for j in (0..n){
            input!{
                s:String,
            }
            if s!="nyanpass" && s!="-"{
                ans-=a[j];a[j]=0;
            }
        }
    }
    if ans!=1{
        print!("{}",-1);
    } else {
        for i in (0..n){
            if a[i]==1{
                print!("{}",i+1);
            }
        }
    }
}