#include <iostream>
#include <algorithm> // for sort, mainly
#include <vector>
#include <map>
#include <set>
#include <cmath>
#include <array>
#include <string>
#include <cstdio>
#include <iterator>
#include <unordered_set>
#include <cstdint> // for int64_t, int32_t, etc
#include <queue>
#include <stack>
#include <deque>
#include <numeric> // gcd, lcm
#include <fstream>
#include <bitset> // for bitset
#include <iomanip>
#include <cassert> // for set with custom ordering
#include <type_traits> // for set with custom ordering
#include <utility> // for swap, forward, etc
using namespace std;
#pragma GCC optimize("O2")
// #pragma GCC optimize("O1","O2","O3","Ofast","unroll-loops")
//#pragma GCC target("sse","sse2","sse3","sse4.1","sse4.2","avx","avx2","fma")
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() { cout << endl; }
template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T) { cout << ' ' << H; dbg_out(T...); }
#ifdef LOCAL
#define dbg(...) cout << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)
#else
#define dbg(...)
#endif
#include "combo.h"
typedef int ll;
string guess_sequence(int N) {
ll n = N;
string ans = "";
// a lenyeg az, hogy hatarozzuk meg, melyik a legelso karakter
ll first = -1;
vector<char> v(4, 'z');
v[0] = 'A';
v[1] = 'B';
v[2] = 'X';
v[3] = 'Y';
for(ll i = 0; i < 4; i++) {
string temp = "" + v[i];
ll g = press(temp);
if(g == 1) {
first = i;
ans += v[i];
break;
}
}
for(ll i = 2; i <= n; i++) {
for(ll j = 0; j < 4; j++) {
if(j == first) {
continue;
}
string temp = ans + v[j];
ll g = press(temp);
if(g == i) {
ans = temp;
break;
}
}
}
return ans;
}
