#ifndef hwe
#include "combo.h"
#endif
#include <bits/stdc++.h>
using namespace std;
#define popcount(n) (__builtin_popcountll((n)))
#define clz(n) (__builtin_clzll((n)))
#define ctz(n) (__builtin_ctzll((n)))
#define lg(n) (63 - __builtin_clzll((n)))
#define BIT(n, i) (((n) >> (i)) & 1ll)
#define MASK(i) (1ll << (i))
#define FLIP(n, i) ((n) ^ (1ll << (i)))
#define ON(n, i) ((n) | MASK(i))
#define OFF(n, i) ((n) & ~MASK(i))
#define Int __int128
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
typedef pair<long long, int> pli;
typedef pair<int, long long> pil;
typedef vector<pair<int, int>> vii;
typedef vector<pair<long long, long long>> vll;
typedef vector<pair<long long, int>> vli;
typedef vector<pair<int, long long>> vil;
template <class T1, class T2>
bool maximize(T1 &x, T2 y) {
if (x < y) {
x = y;
return true;
}
return false;
}
template <class T1, class T2>
bool minimize(T1 &x, T2 y) {
if (x > y) {
x = y;
return true;
}
return false;
}
template <class T>
void remove_duplicate(vector<T> &ve) {
sort (ve.begin(), ve.end());
ve.resize(unique(ve.begin(), ve.end()) - ve.begin());
}
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
template <class T> T random(T l, T r) {
return uniform_int_distribution<T>(l, r)(rng);
}
template <class T> T random(T r) {
return rng() % r;
}
const int N = 1e6 + 5;
const int MOD = 1e9 + 7;
const int inf = 1e9;
const ll INF = 1e18;
string buttons[] = {"A", "B", "X", "Y"};
#ifdef hwe
int press(string p) {
cerr << "Press: " << p << '\n';
int ret; cin >> ret; return ret;
}
#endif
string guess_sequence(int n) {
int first_idx = -1; string ans = "";
for (int i = 0; i < 4; ++i) {
if (press(buttons[i])) {
first_idx = i;
ans = buttons[i];
break;
}
}
assert(first_idx != -1);
int x = -1, y = -1, z = -1;
for (int i = 0; i < 4; ++i) {
if (i == first_idx) continue;
if (x == -1) x = i;
else if (y == -1) y = i;
else z = i;
}
assert(x != -1 && y != -1 && z != -1);
for (int i = 2; i < n; ++i) {
string query = (ans + buttons[x]) + (ans + buttons[y] + buttons[x]) + (ans + buttons[y] + buttons[y]) + (ans + buttons[y] + buttons[z]);
int query_ans = press(query);
if (query_ans == ans.size() + 1) ans += buttons[x];
else ans += buttons[y];
}
string query1 = ans + buttons[x], query2 = ans + buttons[y];
if (press(query1) == n) return query1;
if (press(query2) == n) return query2;
return ans + buttons[z];
}
#ifdef hwe
signed main() {
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
int n; cin >> n;
string ans = guess_sequence(n);
cerr << "Guess: " << ans << '\n';
cerr << '\n'; return 0;
}
#endif
