#include <bits/stdc++.h>
using namespace std;
// #undef _GLIBCXX_DEBUG // disable run-time bound checking, etc
// #pragma GCC optimize("Ofast,inline") // Ofast = O3,fast-math,allow-store-data-races,no-protect-parens
// #pragma GCC optimize ("unroll-loops")
// #pragma GCC target("bmi,bmi2,lzcnt,popcnt") // bit manipulation
// #pragma GCC target("movbe") // byte swap
// #pragma GCC target("aes,pclmul,rdrnd") // encryption
// #pragma GCC target("avx,avx2,f16c,fma,sse3,ssse3,sse4.1,sse4.2") // SIMD
// #include <bits/extc++.h>
// using namespace __gnu_pbds;
// template<class T>using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
// template<class T>using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag,tree_order_statistics_node_update>;
#define ll long long
#define INF (ll)1e9+7
#define fo(i, n) for(int i=0;i<((ll)n);i++)
#define deb(x) cout << #x << " = " << x << endl;
#define deb2(x, y) cout << #x << " = " << x << ", " << #y << " = " << y << endl
#define pb push_back
#define mp make_pair
#define F first
#define S second
#define LSOne(S) ((S) & (-S))
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
inline int readint(){ int v = 0; char c; while((c = getchar()) != EOF && c != ' ' && c != '\n'){ v *= 10; v += c - '0'; } return v; }
inline int readintsigned() { int v = 0; int sign = 1; char c = getchar(); if (c == '-') { sign = -1; } else { v += c - '0'; } while ((c = getchar()) != EOF && c != ' ' && c != '\n') { v *= 10; v += c - '0'; } return v * sign; }
inline string readstring() { string s; char c; while ((c = getchar()) != EOF && c != '\n' && c != ' ') { s.push_back(c); } return s; }
template <class result_t=std::chrono::milliseconds,class clock_t=std::chrono::steady_clock,class duration_t = std::chrono::milliseconds>
auto since(std::chrono::time_point<clock_t, duration_t> const& start){return std::chrono::duration_cast<result_t>(clock_t::now() - start);}
typedef pair<int, int> pii;
typedef pair<ll, ll> pl;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<pii> vpii;
typedef vector<pl> vpl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef vector<vpii> vvpii;
typedef vector<vpl> vvpl;
int press(std::string p);
string alphabet = "ABXY";
string guess_sequence(int n) {
string p = "";
fo(j, 4){
p = "";
fo(i, n) {
p += alphabet[j];
}
if(press(p)) break;
}
for(int i = 1; i < n; i++){
fo(j, 4){
if(alphabet[j] == p[0]) continue;
p[i] = alphabet[j];
if(press(p)>i) break;
}
}
return p;
}
// namespace {
// constexpr int MAX_N = 2000;
// constexpr int MAX_NUM_MOVES = 8000;
// int N;
// std::string S;
// int num_moves;
// void wrong_answer(const char *MSG) {
// printf("Wrong Answer: %s\n", MSG);
// exit(0);
// }
// } // namespace
// int press(std::string p) {
// if (++num_moves > MAX_NUM_MOVES) {
// wrong_answer("too many moves");
// }
// int len = p.length();
// if (len > 4 * N) {
// wrong_answer("invalid press");
// }
// for (int i = 0; i < len; ++i) {
// if (p[i] != 'A' && p[i] != 'B' && p[i] != 'X' && p[i] != 'Y') {
// wrong_answer("invalid press");
// }
// }
// int coins = 0;
// for (int i = 0, j = 0; i < len; ++i) {
// if (j < N && S[j] == p[i]) {
// ++j;
// } else if (S[0] == p[i]) {
// j = 1;
// } else {
// j = 0;
// }
// coins = std::max(coins, j);
// }
// return coins;
// }
// int main() {
// char buffer[MAX_N + 1];
// if (scanf("%s", buffer) != 1) {
// fprintf(stderr, "Error while reading input\n");
// exit(1);
// }
// S = buffer;
// N = S.length();
// num_moves = 0;
// std::string answer = guess_sequence(N);
// if (answer != S) {
// wrong_answer("wrong guess");
// exit(0);
// }
// printf("Accepted: %d\n", num_moves);
// return 0;
// }
