#include "combo.h"
#include<bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
#define all(x) x.begin(), x.end()
using ll = long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
template<typename T>
using matrix = vector<vector<T>>;
std::string guess_sequence(int N) {
string resp;
vector<char> poss = {'A', 'B', 'X', 'Y'};
int ini = 0, fim = 3;
while(ini!=fim){
int m = (ini+fim)>>1;
string guess;
for(int i = ini; i <= m; i++){
guess.push_back(poss[i]);
}
if(press(guess))
fim = m;
else ini = m+1;
}
resp.push_back(poss[ini]);
if(N == 1)
return resp;
poss.erase(poss.begin()+ini);
for(int i = 1; i < N-1; i++){
string guess;
resp.push_back(poss[1]);
guess.append(resp);
resp.pop_back();
resp.push_back(poss[2]);
for(int j = 0; j < 3; j++){
resp.push_back(poss[j]);
guess.append(resp);
resp.pop_back();
}
resp.pop_back();
int ret = press(guess);
resp+=poss[ret-resp.size()];
}
ini = 0, fim = 2;
while(ini!=fim){
int m = (ini+fim)>>1;
string guess;
for(int i = ini; i <= m; i++){
guess.append(resp);
guess.push_back(poss[i]);
}
if(press(guess)-resp.size())
fim = m;
else ini = m+1;
}
resp.push_back(poss[ini]);
return resp;
}
