/* -*- coding: utf-8 -*-
 *
 * 411.cc: No.411 昇順昇順ソート - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

/* global variables */

/* subroutines */

/* main */

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

  int ans = (k > 1) ? (1 << (n - k)) : ((1 << (n - 1)) - n);
  printf("%d\n", ans);
  return 0;
}