var v:array[1..100,1..100]of longint;
    m,n,i,j,k,s,sf1,sf2:longint;
    f,ff:text;
begin
assign(f,'flip.in');reset(f);
assign(ff,'flip.out');rewrite(ff);
read(f,m);
read(f,n);
for i:= 1 to n do
 begin
  s:=0;
 for j:= 1 to m do
  begin
   read(f,v[i,j]);
   s:=s+v[i,j];
  end;
  if s<0 then
  begin
    for k:=1 to m do
     v[i,k]:=v[i,k]*(-1);
 sf1:=sf1+s*(-1);
 end
 else
 sf1:=sf1+s;
 end;
 for j:= 1 to m do
  begin
   s:=0;
   for i:= 1 to n do
    s:=s+v[i,j];
   if s<0 then
    begin
     for k:= 1 to n do
      v[k,j]:=v[k,j]*(-1);
     sf2:=sf2+s*(-1);
    end
   else
   sf2:=sf2+s;
  end;
 if sf1>sf2 then
  write(ff,sf1)
  else
   write(ff,sf2);
close(f);
close(ff);
end.