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

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