#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define v(x) vector<x>
#define pb push_back
#define mp make_pair
const ll maxint=2e18;
const ll minint =-2e18;
int press(string p);
string let[4]={"A","B","X","Y"};
string guess_sequence(int N){
//n=N;
string res ="";
int avoid = 0;
int x = press(let[0]+let[1]);
if(x >= 1){
x = press(let[0]);
if(x == 1){avoid=0;
res+=let[0];
}else {avoid=1;res += let[1];}
}else{
x = press(let[2]);
if(x == 1){
res+=let[2];avoid=2;
}else {avoid=3;res +=let[3];}
}
vector<string> lett;
for(int i=0;i<4;i++)if(i!=avoid)lett.push_back(let[i]);
int i=1;
for(;i<N-1;i++){
x = press((res+lett[0]+lett[0]+res+lett[0]+lett[1]+res+lett[0]+lett[2]+res+lett[1]));
if(x == i+2){
res+=lett[0];
}else if(x == i+1){
res+=lett[1];
}
else{
res += lett[2];
}
}
if(i < N){
x = press(res+lett[0]+res+lett[1]);
if(x == i+1){
x = press(res+lett[0]);
if(x == i+1){
res+=lett[0];
}else res+=lett[1];
}else{
res += lett[2];
}
}
return res;
}
