var   aa,bb,a,b,l,r,mid:longint;

begin
      readln(aa,bb);
      if aa>bb then
        begin a:=bb; b:=aa; end
      else
        begin a:=aa; b:=bb; end;

      l:=a<<1;
      r:=b<<1;

      while l<r do
      begin
            mid:=(l+r)>>1;
            if mid<a+b then l:=mid+1
            else r:=mid;
      end;
      
      writeln(l);
end.