#include <bits/stdc++.h>
#include <iostream>
#include <vector>
#include <cmath>
#include <queue>
#include <map>
#include <algorithm>
#include <iomanip>
#include <set>
#include <cassert>
#include <cstdio>
#include <string>
#include "combo.h"
using namespace std;
string guess_sequence(int N){
string s = "";
vector <string> s0(4);
s0[0] = "A";s0[1] = "B";s0[2] = "X";s0[3] = "Y";
vector <string> v(3);
for(int i = 0;i < 3;i++){
if(press(s+s0[i]) == 1){
s += s0[i];
int ind = 0;
for(int j = 0;j < 4;j++){
if(j == i){
continue;
}
v[ind] = s0[j];
ind++;
}
break;
}
}
if(s == ""){
s += s0[3];
v[0] = "A";
v[1] = "B";
v[2] = "X";
}
int lenght = 1;
string p = "";
while(lenght < N-1){
p = "";
p += s + v[0];
for (int j = 0; j < 3; ++j)
p += s + v[1] + v[j];
int k = press(p);
if(k == lenght){
s += v[2];
lenght++;
}else if(k == lenght + 1){
s += v[0];
lenght++;
}else if(k == lenght + 2){
s += v[1];
lenght++;
}
}
if((int)s.size() == N){
return s;
}
bool found = false;
for(int i = 0;i < 2;i++){
if(press(s+v[i]) > lenght){
s += v[i];
found = true;
break;
}
}
if(!found){
s+= v[2];
}
return s;
}
