#include <fstream>

using namespace std;

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

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