#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <string>
#include <sstream>
#include <cmath>
#include <stack>
#include <cctype>
using namespace std;

int main() {

	int n = 0, d = 0;
	cin >> n >> d;

	int A = 0, B = 0, C = 0;

	if (d - n > 0) {
		A = n - (d - n);
		B = d - n;
	} else if (d - n == 0) {
		A = n;
	} else if (d - n < 0) {
		A = d;
		C = n - d;
	}

	for (int i = 0; i < A; i++) {
		cout << "A";
	}
	for (int i = 0; i < B; i++) {
		cout << "B";
	}
	for (int i = 0; i < C; i++) {
		cout << "C";
	}
	cout<<endl;
	return 0;
}