#include <fstream>
using namespace std;

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

short i,j,n,m;
int a[16][16];
int64_t s,x;

void bk(short o)
{
    if(o<n)
    {
        bk(o+1);
        for(i=0;i<m;++i)
        {
            a[o][i]=-a[o][i];
            s=s+2*a[o][i];
        }
        bk(o+1);
    }
    else
        if(o<m+n)
        {
            bk(o+1);
            for(i=0;i<n;++i)
            {
                a[i][o-n]=-a[i][o-n];
                s=s+2*a[i][o-n];
            }
            bk(o+1);
        }
        else
            if(x<s)
                x=s;
}

int main()
{
    fin>>n>>m;
    for(i=0;i<n;++i)
        for(j=0;j<m;++j)
        {
            fin>>a[i][j];
            s+=a[i][j];
        }
    x=s;
    bk(0);
    fout<<x;
}