var f,g:text;
    a,a1:array[1..16,1..16] of longint;
    i,j,n,m,k:byte;
    s,smax:longint;
    ii,jj,n2,m2,nn,mm:word;
    ok:boolean;
begin
 assign(f,'flip.in');
 assign(g,'flip.out');
 reset(f);
 rewrite(g);
 read (f,n,m);
 for i:=1 to n do begin
  for j:=1 to m do
   read (f,a[i,j]);
   readln(f);
 end;
 smax:=0;
 n2:=1;
 m2:=1;
 for i:=1 to n do n2:=n2*2;
 for j:=1 to m do m2:=m2*2;
 for ii:=0 to n2-1 do
  for jj:=0 to m2-1 do begin
   a1:=a;
   s:=0;
   nn:=27;
   mm:=5;
   for i:=1 to n do begin
    if nn mod 2=0 then for j:=1 to m do a1[i,j]:=-a1[i,j];
    nn:=nn div 2;
   end;
   for j:=1 to m do begin
    if mm mod 2=0 then for i:=1 to n do a1[i,j]:=-a1[i,j];
    mm:=mm div 2;
   end;
   for i:=1 to n do
    for j:=1 to m do s:=s+a1[i,j];
   if s>smax then smax:=s;
  end;
 write(g,smax);
 close(f);
 close(g);
end.