#include <iostream>
#include <vector>
#include <algorithm>
#include <string>

#define REP(i, a, b) for (int i = int(a); i < int(b); i++)

using namespace std;

typedef long long int lli;

int main() {
    int N;
    cin >> N;
    vector<vector<string>> A(N, vector<string>(N));
    REP (i, 0, N) REP (j, 0, N) cin >> A[i][j];
    int nyanpass = -2;
    REP (j, 0, N) {
        int tmp = 0;
        REP (i, 0, N) {
            if (A[i][j] == "nyanpass") tmp++;
        }
        if (tmp == N - 1) {
            if (nyanpass == -2) nyanpass = j + 1;
            else nyanpass = -1;
        }
    }
    cout << max(-1, nyanpass) << endl;
    return 0;
}