#include <stdio.h>
#include <stdlib.h>

int v[17][17],S,sol[34],n,m,i,j;

void check()
{
    int N=0;

    for(i=0;i<n;i++)
    {
        for(j=0;j<m;j++)
        {
            N+=v[i][j]*sol[i]*sol[n+j];
        }
    }

    if(S<N) S=N;
}

void back(int k)
{
    if(k==n+m) check();
    else
    {
        sol[k]=1; back(k+1);
        sol[k]=-1; back(k+1);
    }

}

int main()
{
    FILE *f=fopen("flip.in","r");
    FILE *fp=fopen("flip.out","w");

    fscanf(f,"%d %d",&n,&m);

    for(i=0;i<n;i++)
        for(j=0;j<m;j++)
        {
            fscanf(f,"%d",&v[i][j]);
        }

    back(0);
    fprintf(fp,"%d",S);


    return 0;
}