func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, x, dd[270000];   int main() {     cin >> n >> x;     int limit = (1 << n) - 1;     vector<int> Q;     Q.push_back(0);     for (int i = 1; i <= limit; i++) {       if (i == x) continue;       if (dd[i]) continue;       Q.push_back(i);       dd[(i ^ x)] = 1;     }     cout << Q.size() - 1 << endl;     for (int i = 1; i < Q.size(); i++) {       cout << (Q[i] ^ Q[i - 1]) <<    ;     }   }   