#include <iostream>
#include <fstream>
using namespace std;
int main()
{
    ifstream f("flip.in");
    ofstream g("flip.out");
    short n,m;f>>n>>m;
    int v[17][17],i,j,summin,l,c,suml;
    unsigned long long sum;
    for (i=1;i<=n;i++)
        for(j=1;j<=m;j++)
            f>>v[i][j];
    do
    {
        summin=1;l=0;c=0;
        for(i=1;i<=n;i++)
        {
            suml=0;
            for(j=1;j<=m;j++)
                suml=suml+v[i][j];
            if(suml<summin)
            {
                summin=suml;
                l=i;
            }
        }
        for(j=1;j<=m;j++)
        {
            suml=0;
            for(i=1;i<=n;i++)
                suml=suml+v[i][j];
            if(suml<summin)
            {
                summin=suml;
                c=j;
            }
        }
        if(summin>=0)
            break;
        else
            if(c>0)
                for(i=1;i<=n;i++)
                    v[i][c]=v[i][c]*(-1);
            else
                for(j=1;j<=m;j++)
                    v[l][j]=v[l][j]*(-1);
    }
    while(summin<0);
    sum=0;
    for (i=1;i<=n;i++)
        for(j=1;j<=m;j++)
            sum=sum+v[i][j];
    g<<sum;
    f.close ();
    g.close ();
}