#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
const int C = 26;
void add(int &x, int y) {
  x += y;
  while (x >= MOD) x -= MOD;
  while (x < 0) x += MOD;
}
int fix(int x) {
  while (x >= MOD) x -= MOD;
  while (x < 0) x += MOD;
  return x;
}
int pw(int a, int b) {
  int ret = 1;
  while (b) {
    if (b & 1) ret = 1ll * ret * a % MOD;
    b >>= 1;
    a = 1ll * a * a % MOD;
  }
  return ret;
}
const int MAXN = 1e6 + 10;
int n, x, ans[MAXN], have[MAXN], m, prv;
void solve() {
  cin >> n >> x;
  have[0] = 1;
  for (int i = 1; i < (1 << n); i++) {
    if (!have[i ^ x]) {
      ans[m++] = i;
      have[i] = 1;
    }
  }
  cout << m << "\n";
  for (int i = 0; i < m; i++) {
    cout << (prv ^ ans[i]) << " ";
    prv = ans[i];
  }
  cout << "\n";
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int te = 1;
  for (int w = 1; w <= te; w++) {
    solve();
  }
  return 0;
}
