var f,g:text;
    a,aa:array[1..16,1..16] of longint;
    s,ss,smax:longint;
    k,i,j,n,m:byte;
    x:array[0..16] of byte;
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;
 aa:=a;
 k:=1;
 x[1]:=0;
 while k>0 do begin
  if x[k]<2 then x[k]:=x[k]+1;
  if k=n then begin
   ss:=0;
   for j:=1 to m do begin
    s:=0;
    for i:=1 to n do begin
     if x[i]=2 then a[i,j]:=a[i,j]*(-1);
     s:=s+a[i,j];
    end;
    if s<0 then for i:=1 to n do a[i,j]:=a[i,j]*(-1);
    ss:=ss+s;
   end;
   if ss>smax then smax:=ss;
   while x[k]=2 do begin k:=k-1; end;
  end else begin k:=k+1; x[k]:=0; end;
 end;
 write(g,smax);
 close(f);
 close(g);
end.