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

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    int N; cin >> N;
    vector<vector<string>> A(N, vector<string>(N));
    rep(i,N)rep(j,N) cin >> A[i][j];

    vector<int> can;
    rep(j,N) {
        int ok = 1;
        rep(i,N) ok &= A[i][j] == "nyanpass" || A[i][j] == "-";
        if(ok) can.push_back(j + 1);
    }

    if(can.size() != 1u)
        cout << -1 << endl;
    else
        cout << can[0] << endl;
}