#include <iostream>
#include <fstream>
using namespace std;
int main() {
	ifstream f("flip.in");
	ofstream g("flip.out");
	int m, n, v[101][101], s1 = 0, s2 = 0, i, j, v1[101][101], s3 = 0, s4 = 0,ok=1;
	f >> n >> m;
	for (i = 1; i <= n; i++)
		for (j = 1; j <= m; j++)f >> v[i][j];
	while (ok == 1) {
		ok = 0;
		for (i = 1; i <= n; i++) {
			s1 = 0;
			s2 = 0;
			for (j = 1; j <= m; j++)
			{
				s1 = s1 + v[i][j];
				s2 = s2 + (-1) * v[i][j];
			}
			if (s1 <= s2)for (j = 1; j <= m; j++) {
				v[i][j] = (-1) * v[i][j];
				ok = 1;
			}
		}
		s1 = 0;
		s2 = 0;
		for (j = 1; j <= m; j++) {
			s1 = 0;
			s2 = 0;
			for (i = 1; i <= n; i++)
			{
				s1 = s1 + v[i][j];
				s2 = s2 + (-1) * v[i][j];
			}
			if (s1 <= s2)for (i = 1; i <= n; i++)
			{
				v[i][j] = (-1) * v[i][j]; ok = 1;
			}
		}
	}
	for (i = 1; i <= n; i++) 
		for (j = 1; j <= m; j++)s4 = s4 + v[i][j];  
	
	g << s4;
}