#include<iostream>
#include<cstdio>
#include<cstring>
#include <cstdlib>  
#include <cmath>   
#include<cctype>
#include<string>
#include<set>
#include <map>
#include<algorithm>
#include <functional>
#include<vector>
#include<climits>
#include<stack>
#include<queue>
#include <deque>
#include <climits>
#include <typeinfo>
#include <utility> 
#define all(x) (x).begin(),(x).end()
#define rep(i,m,n) for(int i = m;i < n;++i)
#define pb push_back
#define fore(i,a) for(auto &i:a)
#define rrep(i,m,n) for(int i = m;i >= n;--i)
#define INF INT_MAX/2
using namespace std;
using ll = long long;
using R = double;
const ll MOD = 1e9 + 7;
const ll inf = 1LL << 50;
struct edge { ll from; ll to; ll cost; };



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

	int ans = 0;
	rep(msk, 0, (1 << n)) {
		if (msk == 0 || msk == (1 << n) - 1)continue;
		vector<int>a1;
		vector<int>a2;
		rep(i, 0, n) {
			if (msk & (1 << i)) {
				a1.pb(i);
			}
			else {
				a2.pb(i);
			}
		}
		sort(all(a1));
		sort(all(a2));

		if (a1[0] == k - 1 && a1[a1.size() - 1] > a2[0])ans++;
	}
	cout << ans << endl;

	return 0;
}