// ConsoleApplication1.cpp : Defines the entry point for the console application.
//


#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("flip.in");
ofstream fout("flip.out");
int main()
{
	int tabla[16][16], v[16], n, m, sum = 0;
	fin >> n >> m;
	for (int i = 0; i < n; i++)
	{
		if (i < m) v[i] = 0;
		for (int j = 0; j < m; j++)
			fin >> tabla[i][j];
	}
	for (int i = 0; i < n; i++)
	{
		int s = 0;
		for (int j = 0; j < m; j++)
			s += tabla[i][j];
		if (s < 0)
			for (int j = 0; j < m; j++)
			{
				tabla[i][j] *= -1;
				v[j] += tabla[i][j];
			}
		else for (int j = 0; j < m; j++) v[j] += tabla[i][j];
	}
	for (int j = 0; j < m; j++)
		if (v[j] >= 0)
			sum += v[j];
		else sum += v[j] * -1;

fout << sum;
return 0;
}