func_code_string: #include <bits/stdc++.h>   const int INF = 1e9 + 1;   const int MOD = 1e9 + 7;   using namespace std;   void solve() {     int n;     cin >> n;     vector<int> a(n);     for (int i = 0; i < n; i += 1) cin >> a[i];     ;     sort(a.begin(), a.end());     vector<int> ans;     for (int i = 0; i < n; i += 1) {       for (int j = 0; j < 31; j += 1) {         int pv = a[i] - (1 << j);         int nx = a[i] + (1 << j);         bool pv_find = binary_search(a.begin(), a.end(), pv);         bool nx_find = binary_search(a.begin(), a.end(), nx);         if (pv_find && nx_find) {           ans = {pv, a[i], nx};           break;         } else if (pv_find)           ans = {pv, a[i]};         else if (nx_find)           ans = {a[i], nx};       }       if ((int)ans.size() == 3) break;     }     if (ans.empty()) ans.push_back(a[0]);     cout << (int)ans.size() <<   n ;     for (int i = 0; i < (int)ans.size(); i += 1) cout << ans[i] <<    ;     ;     cout <<   n ;   }   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     solve();     return 0;   }   