#include <iostream>
#include <fstream>
using namespace std;

int main() {
	ifstream in ("flip.in");
	ofstream out ("flip.out");
	int n, m;
	in >> n >> m;
	int a[n+1][m+1] = {0};
	for (int j=0; j<m; j++){
		a[n][j] = 0;
	}
	for (int i=0; i<n; i++){
		a[i][m] = 0;
		for (int j=0; j<m; j++){
			in >> a[i][j];
			a[i][m] += a[i][j];
			a[n][j] += a[i][j];
		}				
	}
	
	int sum = 0;
	for (int i=0; i<n; i++){
		if (a[i][m] < 0){
			for (int j=0; j<m+1; j++){				
				a[n][j] -= 2*a[i][j];
				a[i][j] = -a[i][j];
			}
		}
	}
	for (int j=0; j<m; j++){
		if (a[n][j] < 0){
			for (int i=0; i<n+1; i++){	
				a[i][j] = -a[i][j];
			}
		}
		sum += a[n][j];
	}
	
	out << sum;
	return 0;
}