#include <bits/stdc++.h>
#define rep(i, a, n) for (int i = a; i < n; i++)
#define repr(i, a, n) for (int i = n - 1; i >= a; i--)
using namespace std;
using ll = long long;
using P = pair<int, int>;
template <typename T> void chmin(T &a, T b) { a = min(a, b); }
template <typename T> void chmax(T &a, T b) { a = max(a, b); }

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);

  int n;
  cin >> n;
  string key = "nyanpass";

  vector<vector<string>> v(n, vector<string>(n));
  rep(i, 0, n) rep(j, 0, n) cin >> v[i][j];

  int ans = -1;
  rep(i, 0, n) {
    int c = 0;
    rep(j, 0, n) {
      if (i == j)
        continue;
      if (v[j][i] == key)
        c++;
    }
    if (c == n - 1) {
      if (ans == -1)
        ans = i + 1;
      else {
        ans = -1;
        break;
      }
    }
  }

  cout << ans << endl;
}