#include<fstream>
using namespace std;

ifstream fin("flip.in");
ofstream fout("flip.out");

int a[17][17],n,m,sum,s;

void back(int k)
{
    if(k<=n)
    {
        int j;

        for(j=1;j<=m;j++)
        {
            a[k][j]*=-1;
            s+=2*a[k][j];
        }
        if(s>sum) sum=s;
        back(k+1);
        for(j=1;j<=m;j++)
        {
            a[k][j]*=-1;
            s+=2*a[k][j];
        }
        back(k+1);

    }
    else
        if(k<=n+m)
        {
            int i;

            for(i=1;i<=n;i++)
            {
                a[i][k-n]*=-1;
                s+=2*a[i][k-n];
            }
            if(s>sum) sum=s;
            back(k+1);
            for(i=1;i<=n;i++)
            {
                a[i][k-n]*=-1;
                s+=2*a[i][k-n];
            }
            back(k+1);
        }
}

int main()
{
    int i,j;

    fin>>n>>m;
    for(i=1;i<=n;i++)
        for(j=1;j<=m;j++)
        {
            fin>>a[i][j];
            s+=a[i][j];
        }

    sum=s;
    back(1);
    fout<<sum;

    fin.close(); fout.close();

    return 0;
}