#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <math.h>
#include <cmath>
#include <limits.h>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <functional>
#include <stdio.h>
using namespace std;

long long MOD = 1000000007;

int func( int a ) {
    if ( a == 1 ) { return 0; }
    int ret = 0;
    for ( int i = 2; i <= a; i++ ) {
        ret += 1<<(a-i);
    }
    ret += func( a-1 );
    return ret;
}


int main() {
    int N,K;
    cin >> N >> K;
    if ( K == 1 ) {
        cout << func(N-1) << endl;
    }
    else {
        cout << (1<<(N-K)) << endl;
    }
    return 0;
}