#include<stdio.h>
#include<string.h>
main()
{
long a[20][20],b[20][20],s,i,j,k,v[20],n,m,sp,x,valid,max,print;
FILE *f,*g;
f=fopen("flip.in","r");
g=fopen("flip.out","w");
fscanf(f,"%ld", &n);
fscanf(f,"%ld", &m);
memset(v,0,sizeof(v));
for(i=1;i<=n;i++)
 for(j=1;j<=m;j++)
  fscanf(f,"%ld", &a[i][j]);
print=-100000;
do{
   k=n;
   v[k]++;
   do{
      valid=1;
      if(v[k]>1){ v[k]=0;
		  v[k-1]++;
		  k--;
		  valid=0;
		 }
      }while(valid==0);
  i=1;
  do{
     if(v[i]==1)
      for(j=1;j<=m;j++)
       b[i][j]=-a[i][j];
     else
      for(j=1;j<=m;j++)
       b[i][j]=a[i][j];
     i++;
     }while(i<=n);
  for(j=1;j<=m;j++)
   {
    s=0;
    for(i=1;i<=n;i++)
      s+=b[i][j];
    if(s<0)
     for(i=1;i<=n;i++)
      b[i][j]=-b[i][j];
   }
  max=0;
  for(i=1;i<=n;i++)
   for(j=1;j<=m;j++)
    max+=b[i][j];
  if(max>print)print=max;


  }while(v[0]!=1);
fprintf(g,"%ld",print);

fclose(f);
fclose(g);
return 0;
}