#include<fstream.h>
short a[20][20];
int main(){
ifstream fin("flip.in");
ofstream fout("flip.out");
short n,m;
long S,S1;
fin>>n>>m;
for (int i=0;i<n;i++)
   for (int j=0;j<m;j++)
       fin>>a[i][j];
for (i=0;i<n;i++)      {
     S=0;
     S1=0;
	 for (int u=0;u<m;u++){
	    S+=(-1)*a[i][u];
	    S1+=a[i][u];}
	 if (S>S1)
	    for (u=0;u<m;u++)
	       a[i][u]=a[i][u]*(-1); }
     for (i=0;i<m;i++){
	  S=0;
	  S1=0;
	  for (int u=0;u<n;u++){
	     S+=(-1)*a[u][i];
	     S1+=a[u][i];}
       if (S>S1)
	   for (u=0;u<n;u++)
	       a[u][i]=a[u][i]*(-1);   }
	       long P=0;
     for (i=0;i<n;i++)
	for (int j=0;j<m;j++)
	    P+=a[i][j];
	    fout<<P;
fin.close();
fout.close();
return 0;
}