#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
typedef long long ll;
typedef vector<ll> vll;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<vector<ll>> vvll;
const ll inf = 1e16;
const ll md = 1000000007;

string t[105][105];

int main() {
  int n;
  cin >> n;
  rep(i, n) rep(j, n) cin >> t[i][j];
  int ans = -1;
  rep(j, n) {
    bool flag = false;
    rep(i, n) {
      if(i==j) continue;
      if (t[i][j] != "nyanpass") {
        flag = true;
        break;
      }
    }
    if (flag) continue;
    if (ans == -1)
      ans = j;
    else
      ans = -2;
  }
  if (ans < 0)
    puts("-1");
  else
    cout << ans+1 << endl;
  return 0;
}