#include <bits/stdc++.h>
using namespace std;

int main() {
	int n, k;
	cin >> n >> k;

	int ans = 0;
	for (int i = 0; i < 1 << n; i++) {
		vector<int> a, b;
		for (int j = 0; j < n; j++) {
			if (i & 1 << j) {
				a.push_back(j);
			} else {
				b.push_back(j);
			}
		}
		if (a.empty() || b.empty()) continue;
		sort(a.begin(), a.end());
		sort(b.begin(), b.end());
		if (a.back() > b.front() && a[0] == k - 1) ans++;
	}
	cout << ans << endl;
}