#include <iostream>
#include <vector>
using namespace std;
int main(){
    int N,id=-1;
    cin >> N;
    vector<vector<string>> A(N,vector<string>(N));
    for(int i=0;i<N;i++)for(int j=0;j<N;j++)cin >> A[i][j];
    for(int j=0;j<N;j++){
        int cnt=0;
        for(int i=0;i<N;i++){
            if(!A[i][j].compare("nyanpass"))cnt++;
        }
        if(cnt==N-1){
            if(id==-1)id=j+1;
            else id=N+1;
        }
    }
    if(0<id && id<=N)cout << id << endl;
    else cout << -1 << endl;
    return 0;
}