#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
#include<set>
#include<bitset>
#include<math.h>
#include<map>
#include<queue>
#include<iomanip>
using namespace std;

int main(){
    int n, cnt = 0, f = -1;
    cin >> n;
    vector<vector<string>> v(n, vector<string>(n));
    for (int i = 0; i < n; i++){
        for (int j = 0; j < n; j++){
            cin >> v[i][j];
        }
    }
    for (int i = 0; i < n; i++){
        for (int j = 0; j < n; j++){
            if (v[j][i] == "nyanpass") cnt++;
        }
        if (cnt == n-1){
            if (f == -1) f = i + 1;
            else{
                cout << -1 << endl;
                return 0;
            }
        }
        cnt = 0;
    }
    cout << ((f) ? f : -1) << endl;
}