Problem:
Score : 200 points

Problem Statement

Find the sum of the integers between 1 and N (inclusive), whose sum of digits written in base 10 is between A and B (inclusive).

Constraints

1 \leq N \leq 10^4

1 \leq A \leq B \leq 36

All input values are integers.

Input

Input is given from Standard Input in the following format:

N A B

Output

Print the sum of the integers between 1 and N (inclusive), whose sum of digits written in base 10 is between A and B (inclusive).

Sample Input 1

20 2 5

Sample Output 1

84

Among the integers not greater than 20, the ones whose sums of digits are between 2 and 5, are: 2,3,4,5,11,12,13,14 and 20. We should print the sum of these, 84.

Sample Input 2

10 1 2

Sample Output 2

13

Sample Input 3

100 4 16

Sample Output 3

4554

Solution in OCaml (4.02.3) (judge verdict: Accepted)

let sum_of_digits n =
  let rec aux n' tmp =
    if n' < 1 then tmp else aux (n' / 10) (tmp + n' mod 10)
  in
  aux n 0

let solve n a b =
  let rec aux i ans =
    if i > n then ans
    else match sum_of_digits i with
      | x when a <= x && x <= b -> aux (i + 1) (ans + i)
      | _ -> aux (i + 1) ans
  in
  aux 1 0

let () = Scanf.scanf "%d %d %d" solve |> Printf.printf "%d\n"