var
s:string;
x:longint;
i,c,err:integer;

begin
readln(s);
for i:=1 to length(s) do
  if s[i] in ['1','2','3','4','5','6','7','8','9','0'] then
    begin
    val(s[i],c,err);
    x:=x * 10 + c;
    end;
  
writeln(x * 2);
end.