#include <cstdio>

using namespace std;
int a[17][17],ma=-256000000,n,m,vl[17],vc[17];
void insumare(){
  int i,j,s=0;
  for(i=1;i<=n;i++)
  for(j=1;j<=m;j++)
  {
    if(vl[i]!=vc[j])
      s+=-a[i][j];
    else
      s+=a[i][j];
  }
  if(s>ma)
    ma=s;
}
void bkt(int l,int c){

  if(l==n && c==m)
    insumare();
  else
  {
    if(l<=n){
      vl[l]=1;
      bkt(l+1,c);
      vl[l]=0;
      bkt(l+1,c);
    }
    if(c<=n)
    {
      vc[c]=1;
      bkt(l,c+1);
      vc[c]=0;
      bkt(l,c+1);
    }
  }
}
int main()
{
    FILE *fin=fopen("flip.in","r"),*fout=fopen("flip.out","w");
    int i,j;
    fscanf(fin,"%d%d",&n,&m);
    for(i=1;i<=n;i++)
    for(j=1;j<=m;j++)
    {
      fscanf(fin,"%d",&a[i][j]);
    }
    bkt(1,1);
    fprintf(fout,"%d",ma);
    return 0;
}