#include <bits/stdc++.h>
using namespace std;
void setIO(const string &name = "") {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  if (name.length()) {
    freopen((name + ".in").c_str(), "r", stdin);
    freopen((name + ".out").c_str(), "w", stdout);
  }
}
template <typename T>
void read(vector<T> &a) {
  for (auto &x : a) cin >> x;
}
template <typename T>
void read(vector<T> &a, long long n) {
  a.resize(n);
  for (auto &x : a) cin >> x;
}
template <class T, class U>
ostream &operator<<(ostream &out, const pair<T, U> &v) {
  out << "(";
  out << v.first << "," << v.second;
  return out << ")";
}
template <class T>
ostream &operator<<(ostream &out, const vector<T> &v) {
  out << "[";
  for (auto(i) = 0; (i) < ((long long)(v).size()); (i)++) {
    if (i) out << ", ";
    out << v[i];
  }
  return out << "]";
}
template <typename T>
void print(vector<T> &a) {
  for (const auto &x : a) cout << x << ' ';
  cout << '\n';
}
void MOD(long long &x, long long m = 1000000007) {
  x %= m;
  if (x < 0) x += m;
}
template <typename T>
void dbg(const char *name, T &&arg1) {
  cout << name << " : " << arg1 << '\n';
}
template <typename T, typename... U>
void dbg(const char *names, T &&arg1, U &&...args) {
  const char *comma = strchr(names + 1, ',');
  cout.write(names, comma - names) << " : " << arg1 << " | ";
  dbg(comma + 1, args...);
}
template <class T>
void read(T &x) {
  cin >> x;
}
template <class T, class... U>
void read(T &t, U &...u) {
  read(t);
  read(u...);
}
long long gcd(long long a, long long b) { return !a ? b : gcd(b % a, a); }
long long pow2[19];
void precompute() {
  pow2[0] = 1;
  for (auto(i) = 1; (i) < (19); (i)++) pow2[i] = 2 * pow2[i - 1];
}
long long N, X;
set<long long> s;
bool is_x_ok;
vector<long long> ans_ar;
int32_t main() {
  setIO();
  precompute();
  read(N, X);
  for (auto(i) = 1; (i) < (pow2[N]); (i)++) {
    s.insert(i);
  }
  is_x_ok = (X < pow2[N]);
  if (is_x_ok) s.erase(X);
  long long prev_xor = 0;
  ans_ar.reserve(pow2[N]);
  while (!s.empty()) {
    long long b = *begin(s);
    s.erase(b);
    if (is_x_ok) s.erase(b xor X);
    ans_ar.emplace_back(b xor prev_xor);
    prev_xor = b;
  }
  cout << (long long)(ans_ar).size() << '\n';
  print(ans_ar);
  return 0;
}
