#include "combo.h"
#include <bits/stdc++.h>
using namespace std;/*
string guess_sequence(int n);
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;
}
*/
string guess_sequence(int n) {
string s = "";
vector <char> moves;
char forbid;
int coins;
coins = press("AB");
if(coins){
coins = press("A");
if(coins) forbid = 'A', s += 'A';
else forbid = 'B', s += 'B';
}
else{
coins = press("X");
if(coins) forbid = 'X', s += 'X';
else forbid = 'Y', s += 'Y';
}
for(auto to : {'A', 'B', 'X', 'Y'}){
if(to == forbid) continue;
moves.push_back(to);
}
for(int i = 1; i < n; i++){
coins = press(s+moves[0]+s+moves[1]);
if(coins == i+1){
coins = press(s+moves[0]);
if(coins == i+1){
s += moves[0];
}
else{
s += moves[1];
}
}
else{
s += moves[2];
}
}
return s;
}
