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

int main() {
  int n;
  string s;
  cin >> n;
  vector<int> a(n, 1);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      cin >> s;
      if (s != "nyanpass" && s != "-") a[j] = 0;
    }
  }
  int ans = -1;
  for (int i = 0; i < n; i++) {
    if (a[i]) {
      if (ans != -1) {
        cout << -1 << endl;
        return 0;
      }
      else {
        ans = i + 1;
      }
    }
  }
  cout << ans << endl;
  return 0;
}