#include<stdio.h>
#define dim 101

long a[dim][dim],s,sf;
int n,m,i,j,k;

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

	scanf("%d%d",&n,&m);
	for(i=1;i<=n;++i)
	{
		s=0;
		for(j=1;j<=m;++j)
		{
			scanf("%ld",&a[i][j]);
			s+=a[i][j];
		}
		if(s<0)
		{
			s=0;
			for(j=1;j<=m;++j)
			{
				a[i][j]*=-1;
				s+=a[i][j];
			}
		}
		sf+=s;
	}
	for(j=1;j<=m;++j)
	{
		s=0;
		for(i=1;i<=n;++i)
			s+=a[i][j];
		if(s<0)
		{
			s=0;
			for(i=1;i<=n;++i)
			{
				a[i][j]*=-1;
				s+=a[i][j];
			}
			sf+=2*s;
		}
	}
	printf("%ld",sf);
	return 0;
}