#include <bits/stdc++.h>
#include "combo.h"
using namespace std;
string guess_sequence(int N) {
vector<char> ch={'A','B','X','Y'};
if(press("AB")) {
if(press("B")) swap(ch[0],ch[1]);
} else {
if(press("X")) swap(ch[0],ch[2]);
else swap(ch[0],ch[3]);
}
string ans="";
ans.push_back(ch[0]);
for(int i=1;i<N-1;++i) {
int r=press(ans+ch[1]+ans+ch[2]+ch[1]+ans+ch[2]+ch[2]+ans+ch[2]+ch[3]);
if(r==i) ans.push_back(ch[3]);
else if(r==i+1) ans.push_back(ch[1]);
else ans.push_back(ch[2]);
}
if((int)ans.size()<N) {
if(press(ans+ch[1])==N) ans.push_back(ch[1]);
else {
if(press(ans+ch[2])==N) ans.push_back(ch[2]);
else ans.push_back(ch[3]);
}
}
return ans;
}
