#include <bits/stdc++.h>

 using namespace std;

 int vis[ << ];

 int main()

 {

     int n, x;

     while (cin >> n >> x)

     {

         memset(vis, , sizeof vis);

         vector<int> v;

         if (x >= ( << n))

         {

             for (int i = ; i < ( << n); i++) v.push_back(i);

         }

         else

         {

             for (int i = ; i < ( << n); i++)

             {

                 if (i == x) continue;

                 else if (!vis[i]) { v.push_back(i); vis[i ^ x] = ; }

             }

         }

         cout << v.size() << endl;

         if (!v.empty())

         {

             cout << v[] << " ";

             for (int i = ; i < (int)v.size(); i++) cout << (v[i - ] ^ v[i]) << " ";

             cout << endl;

         }

     }

     return ;

 }