type matrix=array [1..16,1..16] of longint;
var f,g:text;
    s,s2:longint;
    n,m,i,j:integer;
    x:matrix;
begin
  assign (f,'flip.in');
    reset (f);
    read(f,n);
    read(f,m);
    for i:=1 to n do
     begin
       for j:=1 to m do
          read (f,x[i,j]);
       readln;
     end;
  close (f);
  s2:=0;
  for i:=1 to n do
    begin
       s:=0;
      for j:=1 to m do
         s:=s+x[i,j];
      if s<0 then
        for j:=1 to m do x[i,j]:=x[i,j]* -1;
    end;
  for j:=1 to m do
   begin
     s:=0;
     for i:=1 to n do
       s:=s+x[i,j];
     if s<0 then
        for i:=1 to n do x[i,j]:=x[i,j]* -1;
    end;
   for i:=1 to n do
     for j:=1 to m do
     s2:=s2+x[i,j];
  assign(g,'flip.out');
    rewrite (g);
    write (g,s2);
  close (g);
end.