#include <fstream>
#include <ctime>
#define MAX 18
using namespace std;

int main () {
	ifstream fin("flip.in");
	ofstream fout("flip.out");
	short n, m, i, j;
	int s = 0, a[MAX] [MAX];
	fin >> n >> m;
	for (i = 0; i < n; i++ ) {
		for (j = 0; j < m; j++ ) {
			fin >> a[i] [j];
		}
	}
	for (j = 0; j < m; j++ ) {
		for (i = 0 ; i < n; i++ ) {
			s+= a[i] [j];
		}
		if (s < 0) {
			for (i = 0 ; i < n; i++ ) {
				a[i] [j]*= -1;
			}
		}
		s = 0;
	}
	for (i = 0; i < n; i++ ) {
		for (j = 0 ; j < n; j++ ) {
			s+= a[i] [j];
		}
		if (s < 0) {
			for (j = 0 ; j < n; j++ ) {
				a[i] [j]*= -1;
			}
		}
		s= 0;
	}
	for (i = 0; i < n; i++ ) {
		for (j = 0; j < m; j++ ) {
			s+= a[i] [j];
			//fout<< a[i] [j] << " ";
		}
		//fout << endl; 
	}
	fout << s;
	fout.close();
	return 0;
}