#include<iostream>
using namespace std;
const int MAXN = 1e5 + 10;
int n,m,ans;
void f(int n,int m) {
	if (n / 2 + 1 < m) {
		return ;
	}
	if (m == 0) {
		ans++;
		return ;
	}
	for (int i = n;i >= 1;i--) {
		f(i - 2,m - 1);
	}
}
int main() {
	cin >> n >> m;
	f(n,m);
	cout << ans << endl;
	return 0;
}