#include<bits/stdc++.h>
//#define name "InvMOD"
#ifndef name
#include "combo.h"
#endif // name
using namespace std;
string guess_sequence(int n){
string answer = "";
// find first candidate
vector<string> candidate = {"A", "B", "X", "Y"};
auto del_first_can = [&](string x) -> void{
for(int i = 0; i < 4; i++){
if(candidate[i] == x){
answer += x;
candidate.erase(candidate.begin() + i);
break;
}
}
};
if(press("AB")){
if(press("A")){
del_first_can("A");
}
else del_first_can("B");
}
else if(press("X")) del_first_can("X");
else del_first_can("Y");
//cout << "CANDIDATE: " << candidate[0] <<" " << candidate[1] <<" " << candidate[2] << "\n";
for(int i = 1; i < n - 1; i++){
// 4 * (n - 2) + 2 * 3 + 1 < 4 * n
string ask = answer + candidate[0] +
answer + (candidate[1] + candidate[2]) +
answer + (candidate[1] + candidate[0]) +
answer + (candidate[1] + candidate[1]);
assert((int) ask.size() < 4 * n);
int val = press(ask);
if(val == i){
answer = answer + candidate[2];
}
else if(val == i + 1){
answer = answer + candidate[0];
}
else{
answer = answer + candidate[1];
}
//cout << "AFTER ASK: " << i <<" " << answer << "\n";
}
if(n > 1){
if(press(answer + candidate[0]) == n){
answer = answer + candidate[0];
}
else if(press(answer + candidate[1]) == n){
answer = answer + candidate[1];
}
else answer = answer + candidate[2];
}
// total operation = (n - 2) + 2 * 2
return answer;
}
