#include <bits/stdc++.h>
#define rep(i, n) for (ll i = 0; i < n; ++i)
typedef long long ll;
using namespace std;
const int INF = 1e9;

int main() {
    int n;
    cin >> n;
    vector<vector<string>> s(n, vector<string>(n));
    rep(i, n) rep(j, n) cin >> s[i][j];

    int ans = -1;
    rep(j, n) {
        bool flag = true;
        rep(i, n) {
            if (s[i][j] != "nyanpass" && s[i][j] != "-")
                flag = false;
        }

        if (flag) {
            if (ans != -1) {
                cout << -1 << endl;
                return 0;
            }
            ans = j + 1;
        }
    }

    cout << ans << endl;

    return 0;
}