#include<bits/stdc++.h>
using namespace std;
using Int = long long;
//INSERT ABOVE HERE
Int n,k;
Int dp[2][20][1<<20];
int dfs(Int f,Int p,Int b){
  Int &res=dp[f][p][b];
  if(~res) return res;
  if(b+1==(1<<n)) return f;
  res=0;
  for(Int i=0;i<n;i++){
    if((b>>i)&1) continue;
    Int nf=p>i,nb=b|(1<<i);
    if(nf&&f) continue;
    nf|=f;
    res+=dfs(nf,i,nb);
  }
  return res;
};

signed main(){
  cin>>n>>k;
  memset(dp,-1,sizeof(dp));
  k--;
  cout<<dfs(0,k,1<<k)<<endl;
  return 0;
}