#include<stdio.h>
#define max(a,b) a<b?b:a
int n,m,a[17][17],S,st[33],nr,i,j;
int sum()
{int s=0;
 for(i=1;i<=n;i++)
  for(j=1;j<=m;j++)
   s=s+a[i][j]*(st[i]^st[j+n]?-1:1);
 return s;}                                                    
void back()
{if(nr==m+n)
 {int s=sum();
  S=max(s,S);
  return ;}
 nr++;
 st[nr]=0;
 back();
 st[nr]=1;
 back();
 nr--;}
int main()
{freopen("flip.in","r",stdin);
 freopen("flip.out","w",stdout);
 scanf("%d %d",&n,&m);
 for(i=1;i<=n;i++)
  for(j=1;j<=m;j++)
   scanf("%d",&a[i][j]);
 back();
 printf("%d",S);
 fclose(stdout);
 return 0;}