#include <algorithm>
#include <array>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <ostream>
#include<complex>
#include <cmath>
#include <iostream>
#include <stack>
#include <fstream>
#include <queue>
#include <list>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <bitset>
#include <iomanip>
#include <string>
#include <vector>
#include <string>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define ALLOF(c) (c),begin(), (c),end()
typedef long long ll;

int dp(int code,int level)
{
    return 0;
}


int main()
{ 
    int n;
    bool nyabpasu[100];
    fill(nyabpasu,nyabpasu+100,true);
    string tester;
    cin >> n;
    rep(i,n)
    {
        rep(j,n)
        {
            cin >> tester;
            if (tester != "nyanpass" && tester != "-")
            {
                nyabpasu[j] =false;
            }
        }
    }
    int brobable = 0;
    rep(i,n)
    {
        if (nyabpasu[i])
        {
            if (brobable == 0)
            {
                brobable = i+1;
            }
            else
            {
                cout << -1 << endl;
                return 0;
            }
        }
    }
    if (brobable != 0)
    {
        cout << brobable << endl;
        return 0;
    }
    cout << -1  << endl;
    return 0;
}