#include<stdio.h>

FILE *fin, *fout;
long a[16][16],b[16][16];

//char l[16];
int l[16];
int i,j,m,n,nr,lgmax;
long long sc,st,smax;
int main()

{
fin=fopen("flip.in","rt");
fout=fopen("flip.out","wt");
fscanf(fin,"%d %d",&n,&m);
for (i=0;i<n;i++)
    for (j=0;j<m;j++)
       {
       fscanf(fin,"%ld",&a[i][j]);
       sc=smax+=a[i][j];
       }
while (lgmax<=n-1)

     {
     if (l[nr]==1)
	{while (l[nr]==1) nr++;
	 l[nr]=1;
	 if (lgmax<nr) lgmax=nr;
	 for (i=0;i<nr;i++) l[i]=0;
	 nr=0;
	 }
     else if (l[nr]==0) l[nr]=1;

     for (i=0;i<n;i++)
	 for (j=0;j<m;j++)
	     if (l[i]==1) b[i][j]=a[i][j]*(-1);
	     else b[i][j]=a[i][j];
     st=0;
     for (j=0;j<m;j++)
	 {sc=0;
	 for (i=0;i<n;i++)
	   sc+=b[i][j];
	 if (sc<0) sc*=-1;

	 st+=sc;
	 }
     if (smax<st) smax=st;
     }


fprintf(fout,"%ld\n",smax);
fcloseall();
return 0;
}