#include <iostream>
#include <vector>

using namespace std;

int main() {
    int n;
    vector<vector<string>> mat;
    
    cin >> n;
    
    string tmp;
    for (int i = 0; i < n; i++) {
        vector<string> v;
        mat.push_back(v);
        for (int j = 0; j < n; j++) {
            cin >> tmp;
            mat[i].push_back(tmp);
        }
    }
    
    vector<int> lenchon_like;
    for (int j = 0; j < n; j++) {
        int nyanpass_ct = 0;
        for (int i = 0; i < n; i++) {
            if(mat[i][j] == "nyanpass") {
                nyanpass_ct++;
            }
        }
            
        if (nyanpass_ct == n - 1) {
            lenchon_like.push_back(j + 1);
        }
    }
    
    if (lenchon_like.size() == 1) {
        cout << lenchon_like[0] << endl;
    } else {
        cout << -1 << endl;
    }
    
    return 0 ;
}