/*
ID: Yoana Zelova zelova1
PROG:
LANG: C++
*/
#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cmath>
#include<string>
#include<stack>
#include<queue>
#include<vector>
#include<fstream>
using namespace std;
long long n,iu,j,a[64][64],i,ok,br,b,c;
int main()
{
    freopen ("chips.in","r",stdin);
    freopen ("chips.out","w",stdout);
    cin>>n;
    for(i=1;i<=n*2;i++)
    {
        for(j=1;j<=n;j++)
        {
            cin>>a[i][j];
            if(a[i][j]==1)ok++;
        }
    }
    for(i=1;i<=n;i++)
    {
        for(j=1;j<=n;j++)
        {
            if(a[i][j]==1)
            {
                if(a[2*n-i+1][j]==1){cout<<-1<<endl;return 0;}
                br++;
            }
        }
    }
    c=br;
    b=ok-br;
    cout<<min(c,b)<<endl;
    return 0;
}