#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <vector>
#include "combo.h"
using namespace std;
// BEGIN NO SAD
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define trav(a, x) for(auto& a : x)
#define all(x) x.begin(), x.end()
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
typedef vector<int> vi;
#define f first
#define s second
// END NO SAD
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<vector<ll>> matrix;
/*
const string GOAL = "ABX";
int press(string s) {
cerr << "PRESS: " << s << endl;
string want = GOAL;
while(sz(want)) {
for(int i = 0; i + sz(want) <= sz(s); i++) if(s.substr(i, sz(want)) == want) return sz(want);
want = want.substr(0, sz(want)-1);
}
return 0;
}
*/
string guess_sequence(int n) {
string alpha = "ABXY";
int v1 = press("AB");
int v2 = press("AX");
string prefix = "";
if(v1 > 0 && v2 > 0) {
prefix = "A";
alpha.erase(alpha.begin() + 0);
}
else if(v1 > 0 && v2 == 0) {
prefix = "B";
alpha.erase(alpha.begin() + 1);
}
else if(v1 == 0 && v2 > 0) {
prefix = "X";
alpha.erase(alpha.begin() + 2);
}
else if(v1 == 0 && v2 == 0) {
prefix = "Y";
alpha.erase(alpha.begin() + 3);
}
else assert(false);
cerr << "alpha is " << alpha << endl;
while(sz(prefix) < n-1) {
string cand = prefix;
cand += alpha[0];
cand += alpha[0];
cand += prefix;
cand += alpha[0];
cand += alpha[1];
cand += prefix;
cand += alpha[0];
cand += alpha[2];
cand += prefix;
cand += alpha[1];
int pp = press(cand);
if(pp == sz(prefix)+2) prefix += alpha[0];
else if(pp == sz(prefix)+1) prefix += alpha[1];
else if(pp == sz(prefix)+0) prefix += alpha[2];
else assert(false);
}
if(sz(prefix) == n) return prefix;
string lhs = prefix; lhs += alpha[0]; lhs += prefix; lhs += alpha[1];
string rhs = prefix; rhs += alpha[0]; rhs += prefix; rhs += alpha[2];
v1 = press(lhs);
v2 = press(rhs);
if(v1 == n && v2 == n) return prefix + alpha[0];
if(v1 == n) return prefix + alpha[1];
if(v2 == n) return prefix + alpha[2];
assert(false);
}
/*
void solve() {
string ret = guess_sequence(sz(GOAL));
cerr << ret << endl;
cerr << (ret == GOAL) << endl;
}
// what would chika do
// are there edge cases (N=1?)
// are array sizes proper (scaled by proper constant, for example 2* for koosaga tree)
// integer overflow?
// DS reset properly between test cases
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
solve();
}
*/
