//============================================================================
// Name        : JoculFlip.cpp
// Author      : Cristi Rosu
// Version     :
// Copyright   : All rights reserved to Cristi Rosu
// Description : Jocul Flip in C++, Ansi-style
//============================================================================

#include <iostream>
#include <fstream>
using namespace std;
ifstream f("flip.in");
ofstream g("flip.out");

int a[20][20], n, m, i, j;

void afisare(int v[20][20]){
	for(i=1; i<=n; i++){
		for(j=1; j<=m; j++)
			g<<v[i][j]<<" ";
		g<<endl;
	}
}

int main() {
	int s1=0, s2=0, s=0;
	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++){
		for(j=1; j<=m; j++){
			s1+=a[i][j];
			s2+=a[i][j]*(-1);
		}
		if(s2>s1)
			for(j=1; j<=m; j++)
				a[i][j]*=(-1);
		s1=0; s2=0;
	}
	s1=0; s2=0;
	for(j=1; j<=m; j++){
		for(i=1; i<=n; i++){
			s1+=a[i][j];
			s2+=a[i][j]*(-1);
		}
		if(s2>s1)
			for(i=1; i<=n; i++)
				a[i][j]*=(-1);
		s1=0; s2=0;
	}
	for(i=1; i<=n; i++)
		for(j=1; j<=m; j++)
			s+=a[i][j];
	g<<s;
	return 0;
}