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;
        if (m == 0) { c = 1; }
        else
        {
            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);
    }
}