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# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
class Program
{
    private int ranksum(int n)
    {
        string str = n.ToString();
        int s = 0;
        for (int i = 0; i < str.Length; i++)
        {
            s += (int)Char.GetNumericValue(str[i]);
        }
        return s;
    }
    public static void Main()
    {
        Program prog = new Program();
        int n, a, b;
        string[] str = Console.ReadLine().Split(' ');
        n = int.Parse(str[0]);
        a = int.Parse(str[1]);
        b = int.Parse(str[2]);
        int sum = 0;
        for (int j = 1; j <= n; j++)
        {
            if (prog.ranksum(j) >= a && prog.ranksum(j) <= b)
                sum += j;
        }
        Console.WriteLine(sum);
    }
}