#include<bits/stdc++.h>
#define ll long long
#define rep(i,a,b) for(ll i=a;i<=b;i++)
#define ios ios_base::sync_with_stdio(false); cin.tie(NULL);
using namespace std;

ll t1,t2,t3;


int main(){
	ll TESTS=1;
	//cin>>TESTS;
	while(TESTS--){
		ll n,x;
		cin>>n>>x;
		if(n==1 && x==1){
			cout<<0;
			return 0;
		}
		set<ll> s;
		rep(i,1,pow(2,n)-1){
			if(i==x){
				continue;
			}
			ll b=i^x;
			s.insert(min(i,b));
		}
		vector<ll> v;
		for(auto i:s){
			v.push_back(i);
		}
		for(ll i=v.size()-1;i>0;i--){
			v[i]^=v[i-1];
		}
		cout<<v.size()<<endl;
		for(auto i:v){
			cout<<i<<" ";
		}
	}
}