#include<stdio.h>
int n,m;
long a[16][16];
int main()
{
	long s=0,sminus=0,splus=0;
	int i,j,minus=-1,k;
	FILE *f=fopen("flip.in","r"),*g=fopen("flip.out","w");
	fscanf(f,"%d %d",&n,&m);
	for(i=1;i<=n;i++)
	{sminus=0;splus=0;
		for(j=1;j<=m;j++)
		{
			fscanf(f,"%ld",&a[i][j]);
			if(a[i][j]<0)
				sminus+=a[i][j];
			else
				splus+=a[i][j];
		}
		if(sminus*minus>splus)
			for(k=1;k<=m;k++)
				a[i][k]=a[i][k]*minus;
	}
														
	for(i=1;i<=m;i++)
	{sminus=0;splus=0;
		for(j=1;j<=n;j++)
		{				
			if(a[j][i]<0)
				sminus+=a[j][i];
			else
				splus+=a[j][i];
		}
		if(sminus*minus>splus)
		{
			for(k=1;k<=n;k++)
				a[k][i]=a[k][i]*minus;
			s+=minus*(sminus+splus);
		}
		else
			s+=splus+sminus;
	}

	fprintf(g,"%ld",s);
	fclose(g);
	fclose(f);
	return 0;
}