#include <fstream>
using namespace std;
int conditii(int n, int  m, int a[16][16]);
int main()
{
	ifstream fin("flip.in");
	ofstream fout("flip.out");
	int n, m;
	int a[16][16];
	fin >> n >> m;
	for (int i = 0; i < n; i++)
		for (int j = 0; j < m; j++)
			fin >> a[i][j];
	fout<<conditii(n, m, a);
	fin.close();
	fout.close();
}
int conditii(int n, int m, int a[16][16])
{
	int sum1, sum2, i = 0, j = 0, sum = 0;
	while (i < n)
	{
		sum1 = 0;
		sum2 = 0;
		for (int j = 0; j < m; j++)
		{
			sum1 = sum1 + a[i][j];
			sum2 = sum2 + a[i][j] * (-1);
		
		}
		if (sum2 > sum1)
		{
			for (int j = 0; j < m; j++)
				a[i][j] = a[i][j] * (-1);
			i++;
		}
		else
			i++;
	}





	while (j < m)
	{
		sum1 = 0;
		sum2 = 0;
		for (int i = 0; i < n; i++)
		{
			sum1 = sum1 + a[i][j];
			sum2 = sum2 + a[i][j] * (-1);

		}
		if (sum2 > sum1)
		{
			for (int i = 0; i < n; i++)
				a[i][j] = a[i][j] * (-1);
			j++;
		}
		else
			j++;
	}
	for (int i = 0; i < n; i++)
		for (int j = 0; j < m; j++)
			sum = sum + a[i][j];
	return sum;

		
}