#include <iostream>
#include <fstream>

using namespace std;

int a[100][100];
int flip(int n, int m){
	int s1, s2,i,j;
	for (i = 0; i < n; i++){
		s1 = s2 = 0;
		for (j = 0; j < m; j++){
			s1 += a[j][i];
			s2 += -a[j][i];
		}
		if (s1 < s2)
		for (int x = 0; x < n; x++)
			a[x][i] = -a[x][i];
	}

	for (i = 0; i < n; i++){
		s1 = s2 = 0;
		for (j = 0; j < m; j++){
			s1 += a[i][j];
			s2 += -a[i][j];
		}
		if (s1 < s2)
		for (int x = 0; x < m; x++)
			a[i][x] = -a[i][x];
	}
	s1 = 0;
	for (i = 0; i < n; i++)
	for (j = 0; j < m; j++)
		s1 += a[i][j];
	return s1;
}

int main(void)
{
	int n, m, i, j;
	ifstream f("flip.in");
	ofstream g("flip.out");
	f >> n >> m;
	for (i = 0; i < n; i++)
		for (j = 0; j < m; j++)
			f >> a[i][j];
	f.close();
	g<<flip(n, m);
	g.close();

	return 0;
}