#include <stdio.h>

using namespace std;

  FILE *f=fopen("flip.in","r");
  FILE *g=fopen("flip.out","w");



int n,m,a[17][17],x[50],max,nn,i,j,b[17][17];

void afis(int r)
{
  int i,s=0,jj,ii,j;


  for(i=1;i<=n;i++)
  for(j=1;j<=m;j++)
   b[i][j]=a[i][j];

 for(i=1;i<=r;i++)
  if (i<=n)
    {
      if (x[i]==1)for(jj=1;jj<=m;jj++)b[i][jj]=b[i][jj]*-1;
    }
  else
   if (x[i]==1)for(ii=1;ii<=n;ii++)b[ii][i-n]=b[ii][i-n]*-1;


  for(i=1;i<=n;i++)
  for(j=1;j<=m;j++)
  s+=b[i][j];
if (s>max)max=s;

}


void back(int k)
{
  int i;
  for(i=0;i<=1;i++)
  {
   x[k]=i;
   if(k==nn)afis(nn);
   else back(k+1);
  }
}


int main()
{
  max=0;
  fscanf(f,"%d %d",&n,&m);
  for(i=1;i<=n;i++)
  for(j=1;j<=m;j++)
  fscanf(f,"%d",&a[i][j]);

  nn=n+m;
  back(1);


  fprintf(g,"%d",max);
    fclose(g);
    return 0;
}