#include <stdio.h>
int a[260],n,m,sum,suma;
void citire()
{
	int i;
	scanf("%d%d",&n,&m);
	for (i=1; i<=n*m; i++)
	{
		scanf("%d",&a[i]);
		suma+=a[i];
	}
}
void sume()
{
	int i,j;
	for (i=1; i<=m; i++)
	{
		sum=0;
		for (j=i; j<=m*n; j+=m)
			sum+=a[j];
		if (sum<=0)
			suma+=2*sum*-1;
	}
}
void sume2()
{
	int i,j,linie=1,poz;
	for (i=1; i<=n; i++)
	{
		sum=0;
		poz=(linie-1)*m+1;
		for (j=poz; j<=poz+m-1; j++)
			sum+=a[j];
		if (sum<=0)
			suma+=2*sum*-1;
		linie++;
	}
}
int main()
{
	freopen("flip.in","r",stdin);
	freopen("flip.out","w",stdout);
	citire();
	sume();
	sume2();
	//schimbare();
	printf("%d",suma);
	return 0;
}