#include<stdio.h>
#define Nmax 20
/*enum bool
   {
    false,
    true
   };  */
int v[Nmax]={-1},a[Nmax][Nmax];
int s,sum,smax;
int main()
  {bool ok=true;
   register int i,j,n,m;
    freopen("flip.in","rt",stdin);
    freopen("flip.out","wt",stdout);
    scanf("%d%d",&n,&m);
    for(i=0;i<n;++i)
       for(j=0;j<m;++j)
	  scanf("%d",&a[i][j]),smax+=a[i][j];
    while(ok)
    {sum=0;
     for(i=0;i<n;++i)
	{s=0;
	 for(j=0;j<m;++j)
	     s+=a[i][j]*v[j];
	 if(s>-s) sum+=s;
	 else sum-=s;
	}
     if(sum>smax) smax=sum;
     for(i=0;i<m&&1==v[i];++i) v[i]=-1;
     if(i==m) ok=false;
     else v[i]=1;
    }
    printf("%d",smax);
    return 0;
   }