#include <iostream>
#include <fstream>

using namespace std;

int main() {
	int n, m, sl = 0;
	int sc = 0;
	cin >> n >> m;
	int a[17][17];
	int slm = 0;
	for (int i = 1;i <= n;i++) {
		sl = slm = 0;
		for (int j = 1;j <= m;j++)
		{
			cin >> a[i][j];
			sl += a[i][j];
			slm += (a[i][j] * -1);
		}
		if (sl < slm)
			for (int j = 1;j <= m;j++)
				a[i][j] *= -1;
	}
	int scm = 0;
	for (int j = 1;j <= m;j++) {
		scm = sc = 0;
		for (int i = 1;i <= n;i++) {
			scm += (a[i][j] * -1);
			sc += a[i][j];
		}
		if (sc < scm)
			for (int i = 1;i <= n;i++)
				a[i][j] *= -1;
	}
	cout << '\n';
	int s = 0;
	for (int i = 1;i <= n;i++)
		for (int j = 1;j <= m;j++)
			s += a[i][j];
	cout << s;
	return 0;
}