#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cmath>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <sstream>
#include <string>
#define repd(i,a,b) for (int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repd(i,0,n)
#define all(x) (x).begin(),(x).end()
#define mod 1000000007
#define inf 2000000007
#define mp make_pair
#define pb push_back
typedef long long ll;
using namespace std;
template <typename T>
inline void output(T a, int p) {
    if(p) cout << fixed << setprecision(p)  << a << "\n";
    else cout << a << "\n";
}
// end of template

int main() {
    cin.tie(0);
    ios::sync_with_stdio(0);
    // source code
    
    ll N;
    int K;
    cin >> N >> K;
    if(N == 2 && K == 1){
        output(0, 0);
        return 0;
    }
    ll ret = 0;
    repd(a, 2, N + 1){
        
        if(K == a){
            if(a >= 2){
                ret += 1;
                continue;
            }
        }
        
        repd(b, 1, N + 1){
            if (K > a || a <= b || K == b) continue;
            ll tmp = 1;
//            cout << K << "," << a << "," << b;
            repd(i, 1, N + 1){
                if(K == i || a == i || b == i) continue;
                if (K < i && i < a && b < i) tmp *= 2;
                if (!(K < i && i < a) && i < b) tmp = 0;
            }
//            cout << ":" << tmp << endl;
            ret += tmp;
        }
    }
    
    output(ret, 0);
    
    return 0;
}