#include <bits/stdc++.h>
#define OVERRIDE4(a, b, c, d, ...) d
#define REP2(i, n) for (i32 i = 0; i < (i32)(n); ++i)
#define REP3(i, l, r) for (i32 i = (i32)(l); i < (i32)(r); ++i)
#define REP(...) OVERRIDE4(__VA_ARGS__, REP3, REP2)(__VA_ARGS__)
#define PER2(i, n) for (i32 i = (i32)(n)-1; i >= 0; --i)
#define PER3(i, l, r) for (i32 i = (i32)(r)-1; i >= (i32)(l); --i)
#define PER(...) OVERRIDE4(__VA_ARGS__, PER3, PER2)(__VA_ARGS__)
#define LEN(x) (i32)(x).size()
#define ALL(x) begin(x), end(x)
using namespace std;
using i32 = int;
using i64 = long long;
template <typename T>
using V = vector<T>;
template <typename T>
bool chmin(T &x, const T &y) {
    if (x > y) {
        x = y;
        return true;
    }
    return false;
}
template <typename T>
bool chmax(T &x, const T &y) {
    if (x < y) {
        x = y;
        return true;
    }
    return false;
}

#include "combo.h"

string guess_sequence(i32 n) {
    const string chs = "ABXY";
    string ans;
    if (press(chs.substr(0, 2)) > 0) {
        if (press(chs.substr(0, 1)) > 0) {
            ans.push_back(chs[0]);
        } else {
            ans.push_back(chs[1]);
        }
    } else {
        if (press(chs.substr(2, 1)) > 0) {
            ans.push_back(chs[2]);
        } else {
            ans.push_back(chs[3]);
        }
    }
    if (n == 1) {
        return ans;
    }
    string other;
    REP(i, 4) {
        if (chs[i] != ans[0]) {
            other.push_back(chs[i]);
        }
    }
    string cc(2, other[0]);
    string cd = cc;
    cd[1] = other[1];
    string ce = cc;
    ce[1] = other[2];
    string d(1, other[1]);
    while (LEN(ans) < n - 1) {
        string ask = ans + cc + ans + cd + ans + ce + ans + d;
        i32 ret = press(ask);
        if (ret == LEN(ans)) {
            ans.push_back(other[2]);
        } else if (ret == LEN(ans) + 1) {
            ans.push_back(other[1]);
        } else {
            ans.push_back(other[0]);
        }
    }
    REP(i, 2) {
        ans.push_back(other[i]);
        if (press(ans) == n) {
            return ans;
        }
        ans.pop_back();
    }
    ans.push_back(other[2]);
    return ans;
}