// #define local
#include <bits/stdc++.h>
using namespace std;
#ifdef local
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <string>
// #include "combo.h"
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
string guess_sequence(int);
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);
}
cout << "p = " << p << " ret = " << coins << '\n';
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);
cout << "ans = " << answer << '\n';
if (answer != S) {
wrong_answer("wrong guess");
exit(0);
}
printf("Accepted: %d\n", num_moves);
return 0;
}
#else
#include <combo.h>
#endif
string guess_sequence(int n) {
string ans, tmp;
int ret, len = 1;
ret = press("AB");
if (ret >= 1) {
ret = press("A");
if (ret == 1) ans = "A";
else ans = "B";
}
else {
ret = press("X");
if (ret == 1) ans = "X";
else ans = "Y";
}
vector<string> L;
if ("A" != ans) L.push_back("A");
if ("B" != ans) L.push_back("B");
if ("X" != ans) L.push_back("X");
if ("Y" != ans) L.push_back("Y");
string P[4];
P[0] = L[0] + L[0], P[1] = L[0] + L[1], P[2] = L[0] + L[2];
P[3] = L[1];
for (int i = 2; i < n; i++) {
tmp = "";
for (int j = 0; j < 4; j++)
tmp += (ans + P[j]);
ret = press(tmp);
if (ret == len + 2) ans += L[0];
else if (ret == len + 1) ans += L[1];
else if (ret == len) ans += L[2];
len++;
}
ret = press(ans + L[0] + ans + L[1]);
if (ret == len+1) {
ret = press(ans + L[0]);
if (ret == len+1) ans += L[0];
else ans += L[1];
}
else if (ret == len)
ans += L[2];
return ans;
}
