#include <bits/stdc++.h>

using namespace std;

int main() {
    int n;
    cin >> n;
    string a[128][128];

    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            cin >> a[i][j];
        }
    }

    vector<int> vt;
    for (int j = 0; j < n; ++j) {
        int cnt = 0;
        for (int i = 0; i < n; ++i) {
            if (a[i][j] == "nyanpass") cnt++;
        }
        if (cnt == n - 1) vt.push_back(j + 1);
    }

    if (vt.size() == 1) {
        cout << vt[0] << endl;
    } else {
        cout << -1 << endl;
    }
    return 0;
}