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