#include<bits/stdc++.h>
using namespace std;
#include "combo.h"
#define pb push_back
#define sz(a) (int)((a).size())
string guess_sequence(int N) {
string p = "";
vector<char> dif;
if(press("AB")) {
if(press("A")) p = "A";
else p = "B";
}
else if(press("X")) p = "X";
else p = "Y";
if(N == 1) return p;
for(char c : {'A','B','X','Y'})
if(c != p[0])
dif.pb(c);
int last = 1;
for(int i = 1; i < N-1; i++) {
string q = "";
q += p;
q.pb(dif[1]);
for(int j = 0; j < 3; j++) {
q += p;
q.pb(dif[0]);
q.pb(dif[j]);
}
int ans = press(q);
if(ans == sz(p)) p.pb(dif[2]);
else if(ans == sz(p)+1) p.pb(dif[1]);
else p.pb(dif[0]);
assert(sz(p) - last == 1);
last = sz(p);
}
for(int j = 0; j < 2; j++)
if(press(p + dif[j]) == N) return p + dif[j];
return p + dif[2];
}
