#include <iostream>
#include <fstream>
using namespace std;

int main(){
	
	int n, m, S=0;
	
	ifstream f("flip.in");
	f>>n>>m;
	int matrice[n][m];
	for (int i=0;i<n;i++)
		for(int j=0;j<m;j++)
			f>>matrice[i][j];
	f.close();
	
	int ok=1;
	while(ok==1){
             ok=0;    
             for (int i=0;i<n;i++){
                 int S1=0, S2=0;
                 for(int j=0;j<m;j++){
                        S1=S1+matrice[i][j];
                        S2=S2-matrice[i][j];
                        }
                 if (S2>S1){
                        for(int j=0;j<m;j++)
                        matrice[i][j]=matrice[i][j]*-1;
                        ok=1;
                        }
                 }
             
             for (int i=0;i<m;i++){
                 int S1=0, S2=0;
                 for(int j=0;j<n;j++){
                        S1=S1+matrice[j][i];
                        S2=S2-matrice[j][i];
                        }
                 if (S2>S1){
                        for(int j=0;j<n;j++)
                        matrice[j][i]=matrice[j][i]*-1;
                        ok=1;
                        }
                 }
                 
             }
 
    for (int i=0;i<n;i++)
		for(int j=0;j<m;j++)
			S=S+matrice[i][j];	
    	
	ofstream g("flip.out");
	g<<S;
	g.close();
	
	return 0;
}