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 Ruby (2.3.3) (judge verdict: Accepted)

n, a, b = gets.strip.split.map(&:to_i)

# 各桁の和を求める
def digit_sum(n)
    sum = 0
    while n > 0 do
        sum += n % 10
        n /= 10
    end
    sum
end

answer = (1..n)
        .map { |i| [i, digit_sum(i)] }
        .select { |d| a <= d[1] && d[1] <= b }
        .inject(0) { |sum, d| sum + d[0] }

puts answer