C＃でAtCoder Beginners Selection ABC083B Some Sums

自分の書いたコード

using System;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
		int[] NAB = Console.ReadLine().Split(' ').Select(i => int.Parse(i)).ToArray();
		int N = NAB[0];
		int A = NAB[1];
		int B = NAB[2];

		int sum = 0;
		for (int i = 1; i <= N; i++)
		{
			string strI = i.ToString();
			int sum_ = 0;
			foreach(char d in strI)
			{
				sum_ += (int)Char.GetNumericValue(d);
			}
			if (sum_ >= A && sum_ <= B)
			{
				sum += i;
			}
		}
		
		Console.WriteLine(sum);
    }
}