program info3;
var m,n,i,j,suma,suma1,suma2:integer;
v:array[1..16,1..16] of longint;
f:text;
begin
  assign(f,'flip.in'); reset(f); readln(f,n,m);
    for i:=1 to n do begin
    for j:=1 to m do
    read(f,v[i,j]);
    readln(f);
    end;
  close(f);
  {analiza cazurilor}
  for i:=1 to n do begin
  suma:=0;
  for j:=1 to m do
   suma:=suma+v[i,j];
   if suma<0 then
   for j:=1 to m do
    v[i,j]:=-v[i,j];
   end;
  {al doilea for}
   for i:=1 to m do begin
  suma:=0;
  for j:=1 to n do
   suma:=suma+v[j,i];
   if suma<0 then
   for j:=1 to n do v[j,i]:=-v[j,i];
   end;
   suma:=0;
   {suma matrice}
   for i:=1 to n do
    for j:=1 to m do
     suma:=suma+v[i,j];
   assign(f,'flip.out');
   rewrite(f);
   write(f,suma);
   close(f);
   end.