#include <bits/stdc++.h>

using namespace std;

string inp[100][100];

int main()
{
    int n;cin>>n;
    int renge;
    bool found = false;
    for (int i = 0; i < n; ++i) for (int j = 0; j < n; ++j) {
        cin >> inp[i][j];
    }
    for (int i = 0; i < n; ++i) {
        int cnt = 0;
        for (int j = 0; j < n; ++j) {
            if (inp[j][i] == "nyanpass") cnt++;
        }
        if (cnt==n-1) {
            if (found) {
                cout << -1 << endl;
                return 0;
            }
            found = true;
            renge = i + 1;
        }
    }

    cout << (found ? renge : -1) << endl;
}