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 C# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;

namespace AtCorder
{
    class Program
    {
        static void Main(string[] args)
        {
            var input = Console.ReadLine();
            var array = input.Split(' ');
            var n = int.Parse(array[0]);
            var a = int.Parse(array[1]);
            var b = int.Parse(array[2]);
            var result = 0;
            
            for (var i = 1; i <= n; i++)
            {
                var sum = GetSum(i);

                if (a <= sum && sum <= b)
                {
                    result += i;
                }
            }
            
            Console.WriteLine(result);
        }

        static int GetSum(int x)
        {
            var n = x;
            var sum = 0;
            while (0 < n)
            {
                sum += n % 10;
                n /= 10;
            }
            return sum;
        }
    }
}