#include "combo.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
/*
string hidden;
int press(string s) {
set<string> st;
for (int i = 0; i < s.size(); ++i) {
string sub = "";
for (int j = i; j < s.size(); ++j) {
sub += s[j];
st.insert(sub);
}
}
int ans = 0;
for (int i = 1; i <= hidden.size(); ++i) {
string pref = "";
for (int j = 0; j < i; ++j) pref += hidden[j];
if (st.find(pref) != st.end()) ans = i;
}
return ans;
}
*/
int ask(int n, string s, char c) {
string query = s;
for (int i = 1; i <= n; ++i) query += c;
return press(query);
}
string guess_sequence(int n) {
string s = "";
if (press("A") == 1) s += "A";
else if (press("B") == 1) s += "B";
else if (press("X") == 1) s += "X";
else s += "Y";
if (n == 1) return s;
vector<char> c;
for (auto ch : {'A', 'B', 'X', 'Y'}) {
if (ch != s[0]) {
c.push_back(ch);
}
}
while (s.size() < n) {
vector<char> c;
for (auto ch : {'A', 'B', 'X', 'Y'}) {
if (ch != s[0] && ch != s.back()) {
c.push_back(ch);
}
}
int len = s.size();
int x = ask(n, s, c[0]);
if (x != len) {
for (int j = 1; j <= x - len; ++j) s += c[0];
} else {
x = ask(n, s, c[1]);
for (int j = 1; j <= x - len; ++j) s += c[1];
}
}
return s;
}
