#include <fstream>

using namespace std;
int i,j,n,m,s1,s2,sum,k,a[16][16];
int main()
{
    ifstream f("flip.in");
    ofstream g("flip.out");
    f>>n>>m;
    for (i=1; i<=n; i++)
        for (j=1; j<=m; j++) f>>a[i][j];
    for (i=1; i<=n; i++){s1=0;
            s2=0;
        for (j=1; j<=m; j++)
        {
            s1+=a[i][j];
            s2=s2+(-1)*a[i][j];}
            if (s2>s1)

                for (k=1; k<=m; k++) a[i][k]*=-1;

        }
    for (i=1; i<=m; i++){
        s1=0;
            s2=0;
        for (j=1; j<=n; j++)
        {
            s1+=a[j][i];
            s2=s2+a[j][i]*(-1);}
            if (s2>s1)
                for (k=1; k<=n; k++) a[k][i]*=-1;
        }
    for (i=1; i<=n; i++)
        for (j=1; j<=m; j++) sum+=a[i][j];
    g<<sum;
    f.close();
    g.close();
    return 0;
}