#include <iostream>
#include <string>
using namespace std;
int a[101];

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