var f,g:text;
    s1,s,n,m,i,j:longint;
    v:array[1..100,1..16] of integer;
begin
     assign(f,'flip.in');
     reset(f);
     assign(g,'flip.out');
     rewrite(g);
     readln(f,n,m);
          for i:=1 to n do
     begin
         for j:=1 to m do
             read(f,v[i,j]);
         readln;
     end;
        for j:=1 to m do
     begin
          s:=0;
          s1:=0;
         for i:=1 to n do
             begin
                  s:=s+v[i,j];
                  s1:=s1-v[i,j];
             end;
         if s1>s then
            for i:=1 to n do
                v[i,j]:=-v[i,j];
     end;
     for i:=1 to n do
     begin
          s:=0;
          s1:=0;
         for j:=1 to m do
             begin
             s:=s+v[i,j];
             s1:=s1-v[i,j];
             end;
         if s1>s then
            for j:=1 to m do
                v[i,j]:=-v[i,j];
     end;
     s:=0;
     for i:=1 to n do
         for j:=1 to m do
             s:=s+v[i,j];
     write(g,s);
     close(f);
     close(g);
readln;
end.