program flip;
type fl=-1000000..1000000;
var f,g:text; n,m,i,j:byte; A:array[1..16,1..16] of fl; found:boolean;
Smax:longint; st:array[1..32] of shortint;
procedure citire;
begin
Readln(f,n,m);
For i:=1 to n do
 begin
 For j:=1 to m do
  Read(f,A[i,j]);
 Readln(f);
 end;
end;
procedure ver_suma;
var i,j:byte; S:longint;
begin
S:=0;
For i:=1 to n do
 For j:=1 to m do
  S:=S+A[i,j];
If S>Smax then Smax:=S;
end;
procedure suma_max(p:byte);
var i:shortint;  j:byte;
begin
i:=-1;
While i<=1 do
 begin
 st[p]:=i;
 i:=i+2;
 If p<=n then For j:=1 to m do A[p,j]:=A[p,j]*st[p]
         else For j:=1 to n do A[j,p-n]:=A[j,p-n]*st[p-n];
 If p=n+m then ver_suma
          else suma_max(p+1);
 end;

end;
begin
Assign(f,'flip.in'); Reset(f);
Assign(g,'flip.out');Rewrite(g);
citire; Close(f);
Smax:=-100000000;
suma_max(1);
Writeln(Smax);
Write(g,Smax); Close(g);
end.