func_code_string: #include <bits/stdc++.h>   using namespace std;   int query(const vector<int> &S, int v, const vector<int> &T) {     if (S.empty() || T.empty()) return 0;     cout << S.size() <<   n ;     for (int i = 0; i < (int)S.size(); i++)       cout << S[i] + 1 << (i < (int)S.size() - 1 ?     :   n );     cout << T.size() <<   n ;     for (int i = 0; i < (int)T.size(); i++)       cout << T[i] + 1 << (i < (int)T.size() - 1 ?     :   n );     cout << v + 1 <<   n ;     cout << flush;     int answer;     cin >> answer;     return answer;   }   int query(int s, int v, const vector<int> &T) {     return query(vector<int>(1, s), v, T);   }   int N, root;   vector<int> parent;   vector<int> subtree_size;   int main() {     ios::sync_with_stdio(false);     cin >> N;     root = 0;     parent.assign(N, -1);     subtree_size.assign(N, -1);     vector<int> non_root;     for (int i = 0; i < N; i++)       if (i != root) non_root.push_back(i);     for (int i = 0; i < N; i++)       if (i != root) subtree_size[i] = query(root, i, non_root);     subtree_size[root] = N;     vector<int> sorted;     for (int i = 0; i < N; i++) sorted.push_back(i);     sort(sorted.begin(), sorted.end(),          [&](int a, int b) { return subtree_size[a] < subtree_size[b]; });     for (int i = 0; i < N; i++) {       int v = sorted[i];       vector<int> missing_parent;       for (int j = 0; j < i; j++)         if (parent[sorted[j]] < 0) missing_parent.push_back(sorted[j]);       int remaining = query(root, v, missing_parent);       int high = (int)missing_parent.size();       while (remaining > 0) {         int low = 0;         while (low < high) {           int mid = (low + high + 1) / 2;           if (query(root, v,                     vector<int>(missing_parent.begin(),                                 missing_parent.begin() + mid)) == remaining)             high = mid - 1;           else             low = mid;         }         int child = missing_parent[low];         parent[child] = v;         remaining--;       }     }     cout <<  ANSWER  <<   n ;     for (int i = 0; i < N; i++)       if (parent[i] >= 0) cout << i + 1 <<     << parent[i] + 1 <<   n ;     cout << flush;   }   