#include "bits/stdc++.h"
#include "combo.h"
using namespace std;
const int maxn = 2005;
const char buttons[] = {'A', 'B', 'X', 'Y'};
string guess_sequence(int n) {
string ans;
string s;
char ft = 'A';
for(int i = 0; i < 4; ++i) {
if(i == 3) {
ft = buttons[i];
break;
}
s = "";
s += buttons[i];
int x = press(s);
if(x) {
ft = buttons[i];
break;
}
}
string other;
for(int i = 0; i < 4; ++i) {
if(buttons[i] != ft) {
other += buttons[i];
}
}
ans += ft;
for(int len = 2; len <= n; len++) {
if(len == n) {
for(int j = 0; j < 3; ++j) {
s = ans + other[j];
if(press(s) == n) return s;
}
}
s = ans + other[0];
for(int j = 0; j < 4; ++j) {
if(buttons[j] == ft) continue;
s = s + ans + other[1] + buttons[j];
}
int x = press(s) - (int)ans.size();
if(!x) ans += other[2];
else if(x == 1) ans += other[0];
else ans += other[1];
}
return ans;
}
