#include <bits/stdc++.h>

using namespace std;

#define fst(t) std::get<0>(t)
#define snd(t) std::get<1>(t)
#define thd(t) std::get<2>(t)

using ll = long long;
using P = std::tuple<int,int>;

const int dx[8] = {-1, 1, 0, 0, -1, -1, 1, 1}, dy[8] = {0, 0, -1, 1, -1, 1, -1, 1};

int N, K;
ll dp[21];

ll rec(ll x, int n){
    if(dp[x] != -1ll){return dp[x];}

    ll res = 1;
    for(int i=x+1;i<=n;++i){
        res += rec(i, n);
    }

    return res;
}

ll solve(int n, int k){
    memset(dp, -1ll, sizeof(dp));

    if(n == 1){return 0;}
    
    if(k != 1){
        return rec(k, n);
    }

    ll res = 0ll;
    for(int i=1;i<=n-1;++i){
        res += solve(n-1, i);

        memset(dp, -1ll, sizeof(dp));
    }

    return res;
}

int main(){
    //*
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);
    /*/
      /*/

    std::cin >> N >> K;

    std::cout << solve(N, K) << std::endl;
}