#include<fstream.h>
float max,a[17][17];
int n,m;

void back(int k, int l ,int s)
{ if(k==n-1&&l==m) { if(s>max) max=s;} else {
 if(l==m&&k<n-1) back(k+1,0,s);
else { back(k,l+1,s+((a[k][l])*(-1)));
       back(k,l+1,s+a[k][l]); } } }


int main()
{ ifstream f("flip.in");
  ofstream g("flip.out");
 
  f>>n>>m; int i,j;
  for(i=0;i<n;i++)
	  for(j=0;j<n;j++) { f>>a[i][j]; max+=a[i][j]; }
    	    
    back(0,0,0);

  g<<max;
  
  return 0; }