#define _USE_MATH_DEFINES
#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
#include <iterator>
using namespace std;

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

    int ans = 0;
    for(int i=1; i<(1<<n)-1; ++i){
        bitset<20> bs(i);
        int minA = INT_MAX;
        int maxA = INT_MIN;
        int minB = INT_MAX;
        for(int j=0; j<n; ++j){
            if(bs[j]){
                minA = min(minA, j + 1);
                maxA = max(maxA, j + 1);
            }
            else{
                minB = min(minB, j + 1);
            }
        }

        if(k == minA && minB < maxA)
            ++ ans;
    }
    cout << ans << endl;

    return 0;
}