//https://ncode.syosetu.com/n4830bu/239/
#include <bits/stdc++.h>
using namespace std;

int main() {
    int N;
    cin >> N;
    vector A(N, vector<string>(N));
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            cin >> A[i][j];
        }
    }
    const string renchon = "nyanpass";
    vector<int> ans;
    for (int j = 0; j < N; j++) {
        int cnt = 0;
        for (int i = 0; i < N; i++) {
            if (A[i][j] == renchon)
                cnt++;
        }
        if (cnt == N - 1)
            ans.emplace_back(j);
    }
    cout << (ans.size() == 1 ? ans[0] + 1 : -1) << endl;
}