using System;

class Program
{
    const int A = 1000000007;
    static void Main(string[] args)
    {
        var input = Console.ReadLine().Split(' ');
        var n = int.Parse(input[0]);
        var s = int.Parse(input[1]);
        var k = int.Parse(input[2]);

        int m = s - (n - 1) * n * k / 2;
        int c = 0;
        for (var l = 1; l <= n && l <= m; l++)
        {
            long[] t = new long[m - l + 2];
            for (var i = 0; i < t.Length; i++) { t[i] = 1; }
            for (var i = 2; i <= l; i++)
            {
                for (var j = i; j <= m - l; j++)
                {
                    t[j] = (t[j] + t[j - i]) % A;
                }
            }
            c = (int)((c + t[m - l]) % A);
        }
        Console.WriteLine(c);
    }
}