func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 605;   int n;   vector<int> g[N];   map<vector<int>, int> memo;   int ask(vector<int> &vs) {     if (int((vs).size()) <= 1) return 0;     sort((vs).begin(), (vs).end());     if (memo.count(vs)) return memo[vs];     cout <<  ?   << int((vs).size()) << endl;     for (int x = (0), qwerty = (int((vs).size())); x < qwerty; x++) {       if (x) cout <<    ;       cout << vs[x];     }     cout << endl;     int v;     cin >> v;     return memo[vs] = v;   }   pair<int, int> f(vector<int> vs1, vector<int> vs2, bool b) {     if (int((vs1).size()) == 1 && int((vs2).size()) == 1) {       if (!b) {         vector<int> vs = {vs1[0], vs2[0]};         int v = ask(vs);         if (!v) return {-1, -1};       }       return {vs1[0], vs2[0]};     }     vector<int> vs = vs1;     for (int v : vs2) vs.push_back(v);     int A, B, AB, abo;     if (!b)       A = ask(vs1), B = ask(vs2), AB = ask(vs), abo = AB - A - B;     else       abo = 1;     if (!abo) return {-1, -1};     bool rev = 0;     if (int((vs2).size()) == 1) swap(vs1, vs2), rev = 1;     vector<int> vs2_0, vs2_1;     for (int x = (0), qwerty = (int((vs2).size()) / 2); x < qwerty; x++)       vs2_0.push_back(vs2[x]);     for (int x = (int((vs2).size()) / 2), qwerty = (int((vs2).size()));          x < qwerty; x++)       vs2_1.push_back(vs2[x]);     pair<int, int> tmp = f(vs1, vs2_0, 0);     if (tmp.first == -1) tmp = f(vs1, vs2_1, 1);     if (rev) swap(tmp.first, tmp.second);     return tmp;   }   vector<int> cs[2];   int dep[N], par[N];   void dfs(int u, int p, int c) {     cs[c].push_back(u);     for (int v : g[u])       if (v != p) par[v] = u, dep[v] = dep[u] + 1, dfs(v, u, !c);   }   pair<int, int> solve(vector<int> vs) {     vector<int> vs1, vs2;     for (int x = (0), qwerty = (int((vs).size()) / 2); x < qwerty; x++)       vs1.push_back(vs[x]);     for (int x = (int((vs).size()) / 2), qwerty = (int((vs).size())); x < qwerty;          x++)       vs2.push_back(vs[x]);     int A = ask(vs1), B = ask(vs2), AB = ask(vs), ABo = AB - A - B;     if (A) return solve(vs1);     if (B) return solve(vs2);     assert(ABo > 0);     return f(vs1, vs2, 0);   }   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     cin >> n;     vector<int> nused, used;     for (int x = (1), qwerty = (n + 1); x < qwerty; x++) nused.push_back(x);     random_shuffle((nused).begin(), (nused).end());     used.push_back(nused.back());     nused.pop_back();     for (int x = (1), qwerty = (n); x < qwerty; x++) {       pair<int, int> tmp = f(used, nused, 0);       int idx = -1;       for (int i = (0), qwerty = (int((nused).size())); i < qwerty; i++)         if (nused[i] == tmp.second) idx = i;       assert(idx != -1);       swap(nused.back(), nused[idx]);       nused.pop_back();       used.push_back(tmp.second);       sort((used).begin(), (used).end());       g[tmp.first].push_back(tmp.second);       g[tmp.second].push_back(tmp.first);     }     dfs(1, 0, 0);     if (ask(cs[0]) == 0 && ask(cs[1]) == 0) {       cout <<  Y   << int((cs[0]).size()) << endl;       for (int x = (0), qwerty = (int((cs[0]).size())); x < qwerty; x++) {         if (x) cout <<    ;         cout << cs[0][x];       }       cout << endl;     } else {       if (ask(cs[0]) == 0) swap(cs[0], cs[1]);       pair<int, int> tmp = solve(cs[0]);       assert(tmp.first != -1);       vector<int> vs1, vs2;       int u = tmp.first, v = tmp.second;       while (u != v) {         if (dep[u] < dep[v]) {           vs2.push_back(v);           v = par[v];         } else {           vs1.push_back(u);           u = par[u];         }       }       vs1.push_back(u);       reverse((vs1).begin(), (vs1).end());       for (int v : vs2) vs1.push_back(v);       cout <<  N   << int((vs1).size()) << endl;       for (int x = (0), qwerty = (int((vs1).size())); x < qwerty; x++) {         if (x) cout <<    ;         cout << vs1[x];       }       cout << endl;     }   }   