#include "combo.h"
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define eb emplace_back
#define pb push_back
#define ft first
#define sd second
#define pi pair<int, int>
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define dbg(...) dbg_out(__VA_ARGS__)
using ll = long long;
using ld = long double;
using namespace std;
using namespace __gnu_pbds;
//Constants
const ll INF = 5 * 1e18;
const int IINF = 2 * 1e9;
const ll MOD = 1e9 + 7;
// const ll MOD = 998244353;
const ll dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
const ld PI = 3.14159265359;
//Templates
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) {return os << '(' << p.first << ", " << p.second << ')';}
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) {os << '['; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << ']';}
void dbg_out() {cerr << endl;}
template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T) { cerr << H << ' '; dbg_out(T...); }
template<typename T> void mins(T& x, T y) {x = min(x, y);}
template<typename T> void maxs(T& x, T y) {x = max(x, y);}
template<typename T> using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T> using omset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
const string ABC = "ABXY";
string nABC;
string guess_sequence(int n) {
string ans;
int skip;
{
string cur;
for (int i = 0; i < 4; i++) {
cur += ABC[i];
}
if (press(cur.substr(0, 2))) {
if (press(cur.substr(0, 1))) {
skip = 0;
} else {
skip = 1;
}
} else {
if (press(cur.substr(2, 1))) {
skip = 2;
} else {
skip = 3;
}
}
ans.pb(ABC[skip]);
}
for (int i = 0; i < 4; i++) {
if (i == skip) continue;
nABC.pb(ABC[i]);
}
for (int it = 2; it <= n; it++) {
string cur;
int sz = ans.size();
for (int i = 0; i < 3; i++) {
cur += ans;
cur += nABC[i];
}
if (press(cur.substr(0, 2 * (sz + 1))) == it) {
if (press(cur.substr(0, sz + 1)) == it) {
ans.pb(nABC[0]);
} else {
ans.pb(nABC[1]);
}
} else {
ans.pb(nABC[2]);
}
}
return ans;
}
