#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
template <class T, class U>
inline void add_self(T &a, U b) {
  a += b;
  if (a >= mod) a -= mod;
  if (a < 0) a += mod;
}
template <class T, class U>
inline void min_self(T &x, U y) {
  if (y < x) x = y;
}
template <class T, class U>
inline void max_self(T &x, U y) {
  if (y > x) x = y;
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  cout << t;
  ;
  if (sizeof...(v)) cerr << ", ";
  _print(v...);
}
template <class T, class U>
void print_m(const map<T, U> &m, int w = 3) {
  if (m.empty()) {
    cout << "Empty" << endl;
    return;
  }
  for (auto x : m) cout << "(" << x.first << ": " << x.second << ")," << endl;
  cout << endl;
}
template <class T, class U>
void debp(const pair<T, U> &pr, bool end_line = 1) {
  cout << "{" << pr.first << " " << pr.second << "}";
  cout << (end_line ? "\n" : ", ");
}
template <class T>
void print_vp(const T &vp, int sep_line = 0) {
  if (vp.empty()) {
    cout << "Empty" << endl;
    return;
  }
  if (!sep_line) cout << "{ ";
  for (auto x : vp) debp(x, sep_line);
  if (!sep_line) cout << "}\n";
  cout << endl;
}
template <typename T>
void print(const T &v, bool show_index = false) {
  int w = 2;
  if (show_index) {
    for (int i = 0; i < int((v).size()); i++) cout << setw(w) << i << " ";
    cout << endl;
  }
  for (auto &el : v) cout << setw(w) << el << " ";
  cout << endl;
}
template <typename T>
void print_vv(const T &vv) {
  if (int((vv).size()) == 0) {
    cout << "Empty" << endl;
    return;
  }
  int w = 3;
  cout << setw(w) << " ";
  for (int j = 0; j < int((*vv.begin()).size()); j++)
    cout << setw(w) << j << " ";
  cout << endl;
  int i = 0;
  for (auto &v : vv) {
    cout << i++ << " {";
    for (auto &el : v) cout << setw(w) << el << " ";
    cout << "},\n";
  }
  cout << endl;
}
const int nax = (1 << 18);
int main() {
  int n, x;
  while (cin >> n >> x) {
    vector<bool> exc(nax);
    exc[0] = 1;
    vector<int> seq{0};
    for (int i = 1; i < (1 << n); ++i) {
      if (!exc[i ^ x]) {
        exc[i] = 1;
        seq.push_back(i);
      }
    }
    cout << int((seq).size()) - 1 << "\n";
    for (int i = int(1); i < int(int((seq).size())); i++)
      cout << (seq[i - 1] ^ seq[i]) << " ";
    cout << "\n";
  }
  return 0;
}
int main0() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  for (int i = int(1); i < int(30); i++) {
    for (int j = int(i + 1); j < int(30); j++) {
      if ((i ^ j) == 10) {
        cerr << "["
             << "i, j, i ^ j"
             << "] = [";
        _print(i, j, i ^ j);
      }
    }
  }
  return 0;
}
int main1() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  vector<int> a = {1, 3, 1};
  set<int> s;
  for (int i = 0; i < int((a).size()); ++i) {
    int xr = 0;
    for (int j = i; j < int((a).size()); ++j) {
      xr ^= a[j];
      s.insert(xr);
    }
  }
  print(s);
  return 0;
}
