#include <iostream>
#include <algorithm>
#include <string>
#include <cstdio>
using namespace std;

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

    string s[n][n];
    for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) cin >> s[i][j];

    string t = "nyanpass";
    bool f[110] = {};
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            if (i == j) continue;
            if (s[i][j] != t) f[j] = true;
        }
    }

    int a, cnt = 0;
    for (int i = 0; i < n; i++) if (!f[i]) cnt++, a = i + 1;
    cout <<  (cnt == 1 ? a : -1) << endl;

    return 0;
}