#include "combo.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
void DBG() { cerr << "]" << endl; }
template<class H, class... T> void DBG(H h, T... t) { cerr << to_string(h); if(sizeof...(t)) cerr << ", "; DBG(t...); }
#define dbg(...) cerr << "[" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
const int N = 2e5 + 3;
char ELEM[4] = {'A', 'B', 'X', 'Y'};
string guess_sequence(int n) {
string s = "";
string p = string(1, ELEM[0]) + string(1, ELEM[1]);
if (press(p) > 0) {
string c = string(1, ELEM[0]);
if (press(c))
s += c;
else
s += string(1, ELEM[1]);
} else {
string c = string(1, ELEM[2]);
if (press(c))
s += c;
else
s += string(1, ELEM[3]);
}
/// 3 qry
for (int i = 2; i <= n; i++) {
vector<char> vec;
for (int d = 0; d < 4; d++)
if (s[0] != ELEM[d])
vec.push_back(ELEM[d]);
string p = s + vec[0] + s + vec[1];
if (press(p) == i) {
string c = s + vec[0];
if (press(c) == i)
s += vec[0];
else
s += vec[1];
} else {
s += vec[2];
}
}
return s;
}
