#include <iostream>
#include <string>
using namespace std;

int main()
{
    int n;
    cin >> n;

    int num[100] = {};
    string a;
    for(int i = 0; i < n; i++){
        for(int j = 0; j < n; j++){
            cin >> a;
            if(a == "nyanpass") num[j]++;
        }
    }

    int ans,count = 0;
    for(int i = 0; i < n; i++){
        if(num[i] == n - 1){
            count++;
            ans = i + 1;
        }
    }
    
    if(count == 1)
        cout << ans << endl;
    else
        cout << -1 << endl;

    return 0;
}