#include <fstream>
#define Nmax 18

using namespace std;

ifstream f("flip.in");
ofstream g("flip.out");

int n, m;
int a[Nmax][Nmax];
int niv, niv2,stot;
int v[Nmax], w[Nmax];
int ans;

void bkt2(int p)
{
    if(p == niv2+1)
    {
      int s=0;
        for ( int i = 1; i <= niv; i ++ )
            for ( int j = 1; j <= niv2; j ++ )
            s=s+(-1)*a[v[i]][w[j]];
        ans=max(ans, s);
      //for ( int i = 1; i <= niv2; i ++ )
      //  g << w[i] << " ";
     // g << '\n';

    }
    else
    {
        for ( int i = w[p-1]+1; i <= m; i ++ )
        {
            w[p]=i;
            bkt2(p+1);
        }
    }
}

void bkt(int p)
{
    if(p == niv+1)
    { //for ( int i = 1; i <= niv; i ++ )
      //  g << v[i] << " "; g << '\n';
      for (niv2=1; niv2 <= m ; niv2 ++ )
        bkt2(1);
        //g << '\n';
        //g << '\n';
    }
    else
    {
        for ( int i = v[p-1]+1; i <= n; i ++ )
        {
            v[p]=i;
            bkt(p+1);
        }
    }
}

int main()
{
    f >> n >> m;
    for ( int i = 1; i <= n; i ++ )
        for ( int j = 1; j <= m; j ++ )
         f >> a[i][j], stot+=a[i][j];

    for (niv = 1; niv <= n; niv ++ )
        bkt(1);
    g << 2*ans+stot;
    return 0;
}