#include<stdio.h>
long a[20][20],s;
int n,m;
FILE *f=freopen("flip.in","r",stdin),*g=freopen("flip.out","w",stdout);
void col();
void rand();
int main()
{int i,j;
	scanf("%d %d",&n,&m);
	for(i=1;i<=n;i++)
		for(j=1;j<=m;j++) scanf("%ld",&a[i][j]);
	col(); rand();
	for(i=1;i<=n;i++)
		for(j=1;j<=m;j++) s+=a[i][j];
	printf("%ld\n",s);
fclose(f); fclose(g);
return 0;
}
void col()
{int i,j;
 long s2,s3;
	for(j=1;j<=m;j++)
	  {s2=0,s3=0;
		  for(i=1;i<=n;i++) 
		     {s2+=a[i][j];
		      a[i][j]*=(-1);
			  s3+=a[i][j];
		     }
	  if(s2>s3) for(i=1;i<=n;i++) a[i][j]*=(-1);
			 
	}
}
void rand()
{int i,j;
 long s2,s3;
	for(i=1;i<=n;i++)
	  {s2=0,s3=0;
		  for(j=1;j<=m;j++) 
		     {s2+=a[i][j];
		      a[i][j]*=(-1);
			  s3+=a[i][j];
		     }
	  if(s2>s3) for(j=1;j<=m;j++) a[i][j]*=(-1);
	}
}