#include "bits/stdc++.h"
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
static const int INF = 0x3f3f3f3f; static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> static void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> static void amax(T &x, U y) { if(x < y) x = y; }

int main() {
	int N; int K;
	while(~scanf("%d%d", &N, &K)) {
		int ans = 0;
		rep(s, 1 << N) {
			int x[20];
			int a = 0;
			rep(i, N) {
				if(~s >> i & 1)
					x[a ++] = i + 1;
			}
			int b = N;
			rep(i, N) {
				if(s >> i & 1)
					x[a ++] = i + 1;
			}
			if(is_sorted(x, x + N)) continue;
			if(x[0] != K) continue;
			++ ans;
		}
		printf("%d\n", ans);
	}
	return 0;
}