#include <bits/stdc++.h>

using namespace std;

int main(void) {
  int n;
  cin >> n;

  string a[110][110];
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      cin >> a[i][j];
    }
  }

  int cnt = 0, ans = -1;
  for (int i = 0; i < n; i++) {
    bool flag = true;
    for (int j = 0; j < n; j++) {
      if (i == j) continue;
      flag &= (a[j][i] == "nyanpass");
    }
    if (flag) ans = i + 1;
    cnt += flag;
  }

  cout << (cnt == 1 ? ans : -1) << endl;

  return 0;
}