#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

int main() {
  int n;
  cin >> n;
  vector< vector<string> > a(n, vector<string>(n));
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < n; ++j) {
      cin >> a[i][j];
    }
  }

  string t = "nyanpass";
  int ans = -1;
  bool is_valid = true;
  for (int i = 0; i < n; ++i) {
    int cnt = 0;
    for (int j = 0; j < n; ++j) {
      if (a[j][i] == t) cnt++;
    }
    if (ans != -1 && cnt == n - 1) is_valid = false;
    if (cnt == n - 1) ans = i + 1;
  }

  if (ans != -1 && is_valid) cout << ans << '\n';
  else puts("-1");
  return 0;
  
}