#define _USE_MATH_DEFINES
#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <string>
#include <set>
#include <unordered_set>
#include <stack>
#include <iomanip>
#include <unordered_map>
#include <fstream>
#include <queue>
#include <cmath>
using namespace std;
#define int long long
#define ld long double
vector<vector<int>> v(1LL << 18, vector<int>(18, -1));
int n, k;
inline int func(int a, int cur) {
	if (cur == n - 1) return 1;
	if (a + 1 == 1LL << n) return 0;
	int ans = 0;
	int left, right;
	left = max(0LL, cur - k);
	right = min(n - 1, cur + k);
	for (int i = left; i <= right; ++i) {
		if (((a >> i) & 1) == 0) {
			int newa = a | (1LL << i);
			if (v[newa][i] != -1) ans += v[newa][i];
			else ans += func(newa, i);
		}
	}
	v[a][cur] = ans;
	return ans;
}
signed main() {
	cin >> n >> k;
	int a = 1;
	int cur = 0;
	cout << func(a, cur);
}