#include<stdio.h>

int n, m, a[16][16], max=0;

void FlipIt(int h, int v, int* m)
{
	int sum=0;
	for (int i=0; i<n; i++)
	{
		int auxH = h;
		for (int j=0; j<n; j++)
		{
			sum+=((auxH%2^v%2)-0.5)*(-2)*a[i][j];
			auxH=auxH/2;
		}
		v=v/2;
	}
	if (sum>*m)
		*m=sum;
}

int main()
{
	freopen("flip.in", "r", stdin);
	freopen("flip.out", "w", stdout);

	scanf("%d %d", &n, &m);
	for (int i=0; i<n; i++)
		for (int j=0; j<m; j++)
			scanf("%d", &a[i][j]);

	for (int hor=0; hor<1<<n; hor++)
		for (int ver=0; ver<1<<m; ver++)
			FlipIt(hor, ver, &max);

	printf("%d", max);
	return 0;
}