CONST HEX : ARRAY['A'..'F'] OF INTEGER = (10,11,12,13,14,15);
VAR
  str : String;
  Int,
  i   : integer;
BEGIN
  READLN(str);
  Int := 0;
  FOR i := 1 TO Length(str) DO
    IF str[i] < 'A' THEN
      Int := Int * 16 + ORD(str[i]) - 48
    ELSE
      Int := Int * 16 + HEX[str[i]];
  WRITELN(Int);
  READLN;
END.