#include<fstream>
using namespace std;
long a[20][20],b[20][20],s;
int n,m,i,j;
void schimblin(int i)
{
	int s1=0,s2=0;
	for(j=1;j<=m;j++)
		if(a[i][j]>=0)
		s1+=a[i][j];
		else
			s2+=abs(a[i][j]);
			if(s1<s2)
				for(j=1;j<=m;j++)
					if(b[i][j]==0)
				{
					a[i][j]=-a[i][j];
					b[i][j]=1;
				}
}
void schimbcol(int j)
{
	int s1=0,s2=0;
	for(i=1;i<=n;i++)
		if(a[i][j]>=0)
			s1+=a[i][j];
		else
			s2+=abs(a[i][j]);
		if(s1<s2)
			for(i=1;i<=n;i++)
				if(b[i][j]==0)
				{
				a[i][j]=-a[i][j];
				b[i][j]=1;
				}
}
int main()
{
	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];
		f.close();
		for(i=1;i<=n;i++)
			schimblin(i);
		for(j=1;j<=m;j++)
			schimbcol(j);
		
		for(i=1;i<=n;i++)
			for(j=1;j<=m;j++)
				s+=a[i][j];
			g<<s;
		
		return 0;
}