#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll mod = 1e9 + 7;
const ll inf = (1 << 30) - 1;
const ll infll = (1LL << 61) - 1;

int N, cnt, ans = -1;
string a[111][111];
string s = "nyanpass";

int main()
{
    cin >> N;
    map<int, int> mp;
    for (int i = 0; i < N; i++)
    {
        for (int j = 0; j < N; j++)
        {
            cin >> a[i][j];
            if (i != j && a[i][j] == s)
                mp[j]++;
            if (mp[j] == N - 1)
                cnt++, ans = j + 1;
        }
    }
    cout << (cnt == 1 ? ans : -1) << endl;
}