#include <iostream>
#include <string>
using namespace std;
int main() {
    int n, i, j, a = -1, t = 0;
    cin >> n;
    string ar[n][n];
    for (i = 0; i < n; i++) {
        for (j = 0; j < n; j++) {
            cin >> ar[i][j];
        }
    }
    for (i = 0; i < n; i++) {
        for (j = 0; j < n; j++) {
            if ((ar[j][i] != "-") && (ar[j][i] != "nyanpass")) {break;}
            if (j == n - 1) {
                if (a == -1) {a = i + 1;}
                else {t = -1;}
            }
        }
    }
    if (t != -1) {t = a;}
    cout << t << endl;
    return 0;
}