#include<stdio.h>

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

	long a[17][17];
	int i,j,n,m,s,sf=0;
	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)
			for(j=1,s=0;j<=m;++j)
			{
				a[i][j]*=-1;
				s+=a[i][j];
			}
		sf+=s;
	}
	for(i=1;i<=m;++i)
	{
		s=0;
		for(j=1;j<=n;++j)
			s+=a[j][i];
		if(s<0)
		{
			for(j=1,s=0;j<=n;++j)
				{
					a[j][i]*=-1;
					s+=a[j][i];
				}
			sf+=2*s;
		}
	}

	printf("%d",sf);

	return 0;
}