#include <iostream>

using namespace std;

long long fact(long long n)
{
	long long result = 1;
	for (size_t i = 2; i <= n; i++)
	{
		result *= i;
	}

	return result;
}
long long combination(long long n, long long k)
{
	return (fact(n)) / (fact(k)*fact(n - k));
}

long long allWays(int n, int k, int l)
{
	long* result = new long[l];

	for (size_t i = 0; i < l; i++)
	{
		result[i] = n;
	}

	for (size_t i = 0; i < l; i++)
	{
		for (size_t j = 1; j <= k; j++)
		{
			if (i+j < l)
			{
				result[i + j]--;
			}
		}
	}

	long long mainResult = 1;

	for (size_t i = 0; i < l; i++)
	{
		mainResult *= result[i];
	}

	return mainResult;
}

int main()
{
	int n, k, l;

	cin >> n >> k >> l;

	long long result = allWays(n, k, l);

	for (size_t i = 1; i < n; ++i)
	{
		(i % 2 == 0) ? result += combination(n,i)*allWays(n - i, k, l) : result -= combination(n, i)*allWays(n - i, k, l);
	}


	cout << result << endl;
}