#include<stdio.h>

int v[18][18],c[35],n,m,max;
long long sol=-2000000000;

void sum()
{
    int i,j;
    long long s=0;
    for(i=1;i<=n;i++)
        for(j=1;j<=m;j++)
            s+=v[i][j]*c[i]*c[n+j];
    if(s>sol)
        sol=s;
}

void back(int p)
{
    if(p==max+1)
    {
        sum();
        return;
    }
    c[p]=1;
    back(p+1);
    c[p]=-1;
    back(p+1);

}

int main()
{
    freopen("flip.in","r",stdin);
    freopen("flip.out","w",stdout);
    int i,j;
    scanf("%d%d",&n,&m);
    for(i=1;i<=n;i++)
        for(j=1;j<=m;j++)
            scanf("%d",&v[i][j]);
    ////////
    max=n+m;

    back(1);

    printf("%lld\n",sol);
    return 0;
}