#include <fstream.h>
ifstream fin("flip.in");
ofstream fout("flip.out");
int v[16][16];
int sw[32],i,j,n,m,sn,sp,x,k;
int main() {
fin>>n>>m;
for (i=1;i<=n;i++)
	for (j=1;j<=m;j++)
   	fin>>v[i][j];
for (i=1;i<=n;i++)
	{
   sn=0;
   sp=0;
   k++;
	for (j=1;j<=m;j++)
      if (v[i][j]<0)
   		sn+=v[i][j];
      else
      	sp+=v[i][j];
   sn*=-1;
   if (sp<=sn)
     	sw[k]=-1;
   else
   	sw[k]=1;
   }
x=k;
for (i=1;i<=n;i++)
	for (j=1;i<=m;j++)
   	v[i][j]=(v[i][j])*(sw[i]);
for (j=1;j<=m;j++)
	{
   k++;
   sn=0;
   sp=0;
   for (i=1;i<=n;i++)
      if (v[i][j]<0)
      	sn+=v[i][j];
      else
      	sp+=v[i][j];
   sn*=-1;
   if (sp<=sn)
   	sw[k]=-1;
   else
   	sw[k]=1;
   }
for (j=1;i<=n;i++)
	for (i=1;j<=m;j++)
   	v[i][j]=sw[x+j]*v[i][j];
for (i=1;i<=n;i++)
	for (j=1;j<=m;j++)
   	sp+=v[i][j];
fout<<sp;
fin.close();
fout.close();
return 0;
}