#include <fstream>
using namespace std;
ifstream f("flip.in");
ofstream g("flip.out");
int x[21][21], n, m;
int main() {
	f >> n >> m;
	int s1, s2, s3;
	for (int i = 1; i <= n; ++i)
		for (int j = 1; j <= m; ++j)
			f >> x[i][j];
	int tabel[16][16];
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++)
			f >> tabel[i][j];
	}
	for (int i = 0; i < n; i++){
		s1 = 0;
		for (int j = 0; j < m; j++)
			s1 = s1 + tabel[i][j]; 
		if (s1 < 0) 
			for (int j = 0; j < m; j++)
				tabel[i][j] = 0 - tabel[i][j];
	}
	for (int j = 0; j < m; j++){
		s2 = 0;
		for (int i = 0; i < n; i++)
			s2 = s2 + tabel[i][j]; 
		if (s2 < 0) 
			for (int i = 0; i < n; i++)
				tabel[i][j] = 0 - tabel[i][j];
	}
	s3 = 0;
	for (int i = 0; i < n; i++) 
		for (int j = 0; j < m; j++)
			s3 = s3 + tabel[i][j];
	g << s3;
	return 0;
}