#include <bits/stdc++.h>
using namespace std;

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