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

int N, cnt, ans, mp[111];
string a[111][111];

int main()
{
    cin >> N;
    for (int i = 0; i < N; i++)
    {
        for (int j = 0; j < N; j++)
        {
            cin >> a[i][j];
            mp[j] += a[i][j] == "nyanpass";
            if (i != j && mp[j] == N - 1)
                cnt++, ans = j + 1;
        }
    }
    cout << (cnt == 1 ? ans : -1) << endl;
}