#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <cstring>
#include <queue>
#include <stack>
#include <math.h>
#include <iterator>
#include <vector>
#include <string>
#include <set>
#include <math.h>
#include <iostream> 
#include<map>
#include <iomanip>
#include <time.h>
#include <random>
#include <stdlib.h>
#include <list>
#include <typeinfo>
#include <list>
#include <set>
using namespace std;
#define LONG_INF 10000000000000000
#define MAX_MOD 1000000007
#define REP(i,n) for(long long i = 0;i < n;++i)
int main() {
	int n, d;
	cin >> n >> d;
	if (n >= d) {
		for (int i = 0;i < n;++i) {
			if (d != 0) {
				cout << "A";
				d--;
			}
			else {
				cout << "C";
			}
		}
		cout << endl;
		return 0;
	}
	else {
		string s;
		d -= n;
		for (int i = 0;i < n;++i) {
			if (d != 0) {
				s.push_back('B');
				d--;
			}
			else {
				s.push_back('A');
			}
		}
		reverse(s.begin(), s.end());
		cout << s << endl;
		return 0;
	}
}