#include <bits/stdc++.h> #include <ext/pb_ds/assoc_container.hpp> #include <ext/pb_ds/tree_policy.hpp> typedef long long ll; using namespace __gnu_pbds; using namespace std; template <typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>; int query(string str); int N; void cut_first(string &s) { assert(s.size()); reverse(s.begin(), s.end()); s.pop_back(); reverse(s.begin(), s.end()); } string MergeSort(vector<string> t) { if(t.size()==1) return t[0]; vector<string> t1, t2; for(int i=0; i<t.size()/2; ++i) t1.push_back(t[i]); for(int i=t.size()/2; i<t.size(); ++i) t2.push_back(t[i]); string s1 = MergeSort(t1); string s2 = MergeSort(t2); string s = ""; while(s1.size() && s2.size()) { string q = s + s1[0] + s2; if(query(q)==q.size()) { s+=s1[0]; cut_first(s1); } else { s+=s2[0]; cut_first(s2); } } s += s1 + s2; return s; } string pwt(char c, int x) { string s = ""; while(x--) s.push_back(c); return s; } string guess(int n, int S) { N=n; string alph = "abcdefghijklmnopqrstuvwxyz"; vector<string> tab; for(int i=0; i<S; ++i) { tab.push_back(pwt(alph[i], query(pwt(alph[i],n)))); } return MergeSort(tab); }