#include<fstream.h>
int a[17][17];
int main()
{
	int m,n,s=0,s1=0,i,j;
	ifstream f("flip.in");
	ofstream g("flip.out");
	f>>n>>m;
	for (i=1;i<=n;i++)
		for (j=1;j<=m;j++)
			f>>a[i][j];
	for (i=1;i<=n;i++){
		s=0;
		for (j=1;j<=m;j++)
			s+=a[i][j];
		s1=0;
		for (j=1;j<=m;j++)
			if (a[i][j]>=0) s1+=a[i][j]-(2*a[i][j]);
			else s1+=abs(a[i][j]);
		if (s1>s) 
			for (j=1;j<=m;j++)
				if (a[i][j]>=0) a[i][j]=a[i][j]*-1;
				else a[i][j]=abs(a[i][j]);
	}
	for (j=1;j<=m;j++){
		s=0;
		for (i=1;i<=n;i++)
			s+=a[i][j];
		s1=0;
		for (i=1;i<=n;i++)
			if (a[i][j]>=0) s1+=a[i][j]-(2*a[i][j]);
			else s1+=abs(a[i][j]);
		if (s1>s) 
			for (i=1;i<=n;i++)
				if (a[i][j]>=0) a[i][j]=a[i][j]*-1;
				else a[i][j]=abs(a[i][j]);
	}
	s=0;
	for (i=1;i<=n;i++)
		for (j=1;j<=m;j++)
			s+=a[i][j];
	g<<s;
	return 0;
}