#include<bits/stdc++.h>
using namespace std;
int main(){
    int N; cin >> N;
    string nyan[N][N];
    for(int i=0; i<N; i++){
        for(int j=0; j<N; j++){
            cin >> nyan[i][j];
        }    
    }
    int cnt = 0, judge = 0;
    for(int i=0; i<N; i++){
        for(int j=0; j<N; j++){
            if(nyan[j][i] == "nyanpass"){
                cnt++;
                if(cnt == N-1){
                    judge++;
                    cout << i+1 << endl;
                    break;
                }
            }
        }
    }
    if(judge != 1){
        cout << -1 << endl;
    }
    return 0;
}