Program flip;
 var a: array [1..16,1..16] of longint;
   s1,s2,s,i,j,n,m:longint;
   t:boolean;
   fi,fo:text;
begin
 assign(fi,'flip.in');
  reset(fi);
 assign(fo,'flip.out');
  rewrite(fo);
   readln(fi,n,m);
 for i:=1 to n do begin
  for j:=1 to m do
   read(fi,a[i,j]) ;
    readln(fi);
     end;
    repeat
    t:=true;
  for i:=1 to n do begin
   for j:=1 to m do begin
    s1:=s1+a[i,j];
    s2:=s2-a[i,j];
     end;
      if s2>=s1 then begin
                   for j:=1 to m do
                     a[i,j]:=-a[i,j];
                   t:=false;
                   end;
          s1:=0; s2:=0;
           end;
           s1:=0; s2:=0;
  for i:=1 to m do begin
   for j:=1 to n do begin
    s1:=s1+a[j,i];
    s2:=s2-a[j,i];
    end;
     if s2>=s1 then  begin
                  for j:=1 to n do
                   a[j,i]:=-a[j,i];
                  t:=false;
                  end;
        s1:=0; s2:=0;
        end;
       until t=true;
  for i:=1 to n do
   for j:=1 to m do
      s:=s+a[i,j];
  write(fo,s);
  close(fo);
end.