//#define NDEBUG
#include <bits/stdc++.h>
#include <bits/extc++.h>
#include "combo.h"
#define StarBurstStream ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define iter(a) a.begin(), a.end()
#define riter(a) a.rbegin(), a.rend()
#define lsort(a) sort(iter(a))
#define gsort(a) sort(riter(a))
#define mp(a, b) make_pair(a, b)
#define pb(a) push_back(a)
#define eb(a) emplace_back(a)
#define pf(a) push_front(a)
#define pob pop_back()
#define pof pop_front()
#define F first
#define S second
#define printv(a, b) {bool pvaspace=false; \
for(auto pva : a){ \
if(pvaspace) b << " "; pvaspace=true;\
b << pva;\
}\
b << "\n";}
#define pii pair<int, int>
#define pll pair<ll, ll>
#define tiii tuple<int, int, int>
#define mt make_tuple
#define gt(t, i) get<i>(t)
#define iceil(a, b) ((a) / (b) + !!((a) % (b)))
//#define TEST
typedef long long ll;
typedef unsigned long long ull;
using namespace std;
using namespace __gnu_pbds;
const ll MOD = 1000000007;
const ll MAX = 2147483647;
template<typename A, typename B>
ostream &operator<<(ostream &o, pair<A, B> p){
return o << '(' << p.F << ',' << p.S << ')';
}
string guess_sequence(int N){
string s;
vector<char> v = {'X', 'Y', 'A', 'B'};
if(press(string(1, v[0]) + string(1, v[1])) >= 1){
if(press(string(1, v[0]))){
s += v[0];
}
else{
s += v[1];
swap(v[0], v[1]);
}
}
else{
if(press(string(1, v[2]))){
s += v[2];
swap(v[0], v[2]);
}
else{
s += v[3];
swap(v[0], v[3]);
}
}
for(int i = 1; i < N - 1; i++){
string t = s + v[1] + s + v[2] + v[1] + s + v[2] + v[2] + s + v[2] + v[3];
// cerr << t << "\n";
int tmp = press(t);
if(tmp == i) s += v[3];
else if(tmp == i + 1) s += v[1];
else s += v[2];
}
if(press(s + v[1]) == N){
s += v[1];
}
else if(press(s + v[2]) == N){
s += v[2];
}
else s += v[3];
return s;
}
