#include <fstream>
#include <iostream>

using namespace std;

ifstream fin ("flip.in");
ofstream fout ("flip.out");

int n, m, s, a[16][16];

void cit(){
	fin >> n >> m;
	for (int i = 0; i < n; i++){
		s = 0;
		for (int j = 0; j < m; j++){
			fin >> a[i][j];
			s += a[i][j];
		}
		if (-s > s)
			for (int j = 0; j < m; j++)
				a[i][j] = -a[i][j];
	}
	
	for (int j = 0; j < m; j++){
		s = 0;
		for (int i = 0; i < n; i++){
			s += a[i][j];
		}
		if (-s > s)
			for (int i = 0; i < n; i++)
				a[i][j] = -a[i][j];
	}
}

void rez(){
	s = 0;
	for (int i = 0; i < n; i++)
		for (int j = 0; j < m; j++) 
			s += a[i][j];
	fout << s;
}

int main(){
	cit();
	rez();
	return 0;
}