#include "combo.h"
#include <bits/stdc++.h>
using namespace std;
string guess_sequence(int n) {
char pre=' ';
string cur="";
vector<char> other(0),buttons={'A','B','X','Y'};
//find s[0] (2)
int ab=press("AB"),ax=press("AX");
if (ab&&ax) pre='A';
else if (ab) pre='B';
else if (ax) pre='X';
else pre='Y';
for (char ch:buttons){
if (pre!=ch) other.push_back(ch);
}
cur+=pre;
if (n==1) return cur;
//find s[1..n-2] (n-2)
for (int i=1;i<n-1;i++){
string s1=cur+other[0],s2=cur+other[1];
string s2a=s2+other[0],s2b=s2+other[1],s2c=s2+other[2];
int res=press(s1+s2a+s2b+s2c);
if (res==i+2) cur+=other[1];
else if (res==i+1) cur+=other[0];
else cur+=other[2];
}
//find s[n-1] (2)
int cur1=press(cur+other[0]),cur2=press(cur+other[1]);
if (cur1==n) return cur+other[0];
else if (cur2==n) return cur+other[1];
else return cur+other[2];
}
