#include "combo.h"
#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair < int, int > pii;
typedef pair < ll, ll > pll;
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define SZ(x) (int)x.size()
#define Mp make_pair
#define endl "\n"
#define fast_io ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
const int N = 1e6 + 10;
const int LOG = 20;
const ll mod = 1e9 + 7;
const ll inf = 8e18;
string A[4] = {"A", "B", "X", "Y"};
vector < string > vec;
string guess_sequence(int n)
{
mt19937 rng(58);
string ans;
shuffle(A, A + 4, rng);
for(int j = 0; j < 3; j ++)
{
if(press(A[j]))
{
ans += A[j];
break;
}
}
if(ans == "") ans += A[3];
for(int j = 0; j < 4; j ++)
{
if(ans == A[j]) continue;
vec.push_back(A[j]);
}
int last = -1;
for(int i = 1; i < n; i ++)
{
vector < int > opt;
for(int j = 0; j < 3; j ++)
{
if(j == last) continue;
opt.push_back(j);
}
for(int k = 0; k < SZ(opt) - 1; k ++)
{
int j = opt[k];
int now = press(ans + vec[j] + vec[j]);
if(now == i)
{
continue;
}
if(now == i + 1)
{
last = j;
ans += vec[j];
break;
}
if(now == i + 2)
{
ans += vec[j] + vec[j];
i ++;
last = -1;
break;
}
}
if(SZ(ans) == i)
{
ans += vec[opt.back()];
last = -1;
}
}
return ans;
}
