var a:array[1..16,1..16]of longint; s,s2:int64; i,j,n,m:byte;
procedure gen(i,j:byte);
var i1,i2:byte;
begin
  s2:=0;
  for i1:=1 to n do for i2:=1 to m do s2:=s2+a[i1,i2];
  if s2>s then s:=s2;
  for i1:=i to n do begin
    for i2:=1 to m do a[i1,i2]:=-a[i1,i2];
    gen(i1+1,j);
  end;
    for i2:=j to m do begin
    for i1:=1 to n do a[i1,i2]:=-a[i1,i2];
    gen(i,i2+1);
  end;
end;
begin
assign(input,'flip.in'); reset(input);
read(n,m);
for i:=1 to n do for j:=1 to m do read(a[i,j]);
gen(1,1);
assign(output,'flip.out'); rewrite(output);
writeln(s);
close(output);
end.