#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;

int main() {
  int N; cin >> N;
  vector<bool> ans(N, true);
  for(int i = 0; i < N*N; i++){
    string A; cin >> A;
    if(A == "-") continue;
    if(A != "nyanpass") ans[i%N] = false;
  }
  vector<int> S(0);
  for(int i = 0; i < N; i++){
    if(ans[i]) S.push_back(i+1);
  }
  if((int)S.size() == 1) cout << S[0] << endl;
  else cout << -1 << endl;
}