#include<iostream>

using namespace std;

int main() {
	
	int n, d;

	cin >> n >> d;
	if (2 * n >= d) {
		if (n > d) {
			int amari = d % n;
			for (int i = 0;i < n - amari;i++) cout << 'A';
			for (int i = 0;i < amari;i++)cout << 'C';
			cout << endl;
		}
		else if (n == d) {
			for (int i = 0;i < n;i++)cout << 'A';
			cout << endl;
		}
		else if (n < d) {
			int amari = d % n;
			for (int i = 0;i < n - amari;i++)cout << 'A';
			for (int i = 0;i < amari;i++)cout << 'B';
			cout << endl;
		}
		else if (2 * n == d) {
			for (int i = 0;i < n;i++) cout << 'B';
			cout << endl;
		}
	}

	return 0;
}