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