var f,t:text;
    a,b:longint;
begin
assign(f,'adunare.in');
assign(t,'adunare.out');
reset(f);
read(f,a);read(f,b);
close(f);
rewrite(t);
if  ((a+b) mod 2 = 0) then write(t,a+b)
                           else begin
                           write(t,b+a);
                           while a<>b do
                           if a>b then if (a-2)=b then a:=a-1
                                                  else a:=a-2
                                  else if (b-2)=a then b:=b-1
                                                  else b:=b-2;
                           end;




close(t);
end.