type tabel=array[1..16,1..16]of longint;
var t,x:tabel;
    n,m,i,j,smax,s1,s2,k:longint;
begin
 assign(input,'flip.in');
 reset(input);
   readln(n,m);
   for i:=1 to n do
    begin
     for j:=1 to m do
      read(t[i,j]);
      readln;
    end;
 close(input);

 smax:=0;
 for i:=1 to n do
  for j:=1 to m do
   x[i,j]:=t[i,j]*(-1);

    s1:=0;
 s2:=0;

   for i:=1 to n do
    begin
      for j:=1 to m do
       begin
       s1:=s1+t[i,j];
       s2:=s2+x[i,j];
       end;
     if s2>s1 then for k:=1 to m do t[i,k]:=t[i,k]*(-1);
    s1:=0;
 s2:=0;

  end;

   for i:=1 to n do
    begin
     s1:=0;
     s2:=0;
      for j:=1 to m do
       begin
       s1:=s1+t[j,i];
       s2:=s2+x[j,i];
       end;
     if s2>s1 then for k:=1 to n do t[k,i]:=t[k,i]*(-1);
      s1:=0;
 s2:=0;
end;
   for i:=1 to n do
    for j:=1 to m do
    smax:=smax+t[i,j];

    assign(output,'flip.out');
    rewrite(output);
     write(smax);
    close(output);
end.