#include "stdafx.h"
#include<iostream.h>
#include<fstream.h>
ifstream f("flip.in");
ofstream g("flip.out");
int max, s, j, i, n, m, a[100][100], v[1000],nr,b[100][100];
using namespace std;
void sol()
{
	nr++;
	int suma = 0;
	int p;
	for (p = 1; p <= m + n; p++)
	{if (v[p] == 2)v[p] = -1;
}
	
	int c = 0;
	for (i = 1; i <= n; i++)
	{
		c++; if (v[c]==-1)
		for (j = 1; j <= m; j++)
			a[i][j] = a[i][j] * v[c];
	}
	for (j = 1; j <= m; j++)
	{
		c++; if (v[c] == -1)
		for (i = 1; i <= n; i++)
			a[i][j] = a[i][j] * v[c];
	}

	for (i = 1; i <= n; i++)
	for (j = 1; j <= m; j++)
		suma = suma + a[i][j];
	

	if (max < suma)
		max = suma;
		
}
	
	
void back(int k)
{
	int p;
	for (p = 1; p <= 2; p++)
	{
		v[k] = p;
		if (k == n + m)sol();
		else back(k + 1);
	}

}
int main()
{
	nr = 0;
	f >> n >> m;
	for (i = 1; i <= n; i++)
	for (j = 1; j <= m; j++)
	{
		f >> a[i][j]; s = s + a[i][j];
	}max = s; 
	back(1); g << max ;
	return 0;
}