// #define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
int main() {
    // Input
    int N;
    cin >> N;
    vector<vector<string>> A(N, vector<string>(N));
    rep(i, N) rep(j, N) cin >> A[i][j];

    // Judge
    const string key = "nyanpass";
    int cnt = 0;
    int idx;
    rep(j, N) {
        bool isRenchon = true;
        rep(i, N) if (i != j && A[i][j] != key) isRenchon = false;
        if (isRenchon) ++cnt, idx = j + 1;
    }

    // Output
    cout << (cnt == 1 ? idx : -1) << endl;
}