#include <fstream>
using namespace std;

int n,m;

int reverse_coloana(int a[100][100],int j)
{	
	int i;
	for(i=1; i<=n; i++)
	a[i][j]=a[i][j]*-1;
	
	return 0;
}

int reverse_line(int a[100][100],int i)
{
	int j;
	for(j=1; j<=m; j++)
	a[i][j]=a[i][j]*-1;
	
	return 0;
}

int main ()
{
	ifstream f("flip.in");
	ofstream g("flip.out");
	
	int i,j,a[100][100],suma1,suma2;
	
	f>>n>>m;
	
	for(i=1; i<=n; i++)
		for(j=1; j<=m; j++)
			f>>a[i][j];
			
	//linie
	for(i=1; i<=n; i++)
		{
			suma1=0; suma2=0;
			for(j=1; j<=m; j++)
				{
					suma1+=a[i][j];	
					suma2+=a[i][j]*-1;
				}
			if(suma2>suma1)
				reverse_line(a,i);
		}
		
	//coloana
	for(j=1; j<=m; j++)
		{
			suma1=0; suma2=0;
			for(i=1; i<=n; i++)
				{
					suma1+=a[i][j];	
					suma2+=a[i][j]*-1;
				}
			if(suma2>suma1)
				reverse_coloana(a,j);
		}
		
	//suma finala
	suma1=0;
	for(i=1; i<=n; i++)
		for(j=1; j<=m; j++)
			suma1+=a[i][j];
			
			
	g<<suma1;
	
	return 0;
}