#include <iostream>

const char zero = 'C';
const char one = 'A';
const char two = 'B';

int main() {
	int n;
	int d;
	std::cin >> n >> d;
	switch (d / n) {
	case 2: for (int i = 0; i < n; i++) {
				std::cout << two;
			}
			break;
	case 1: for (int i = 0; i < 2 * n - d; i++) {
				std::cout << one;
			}
			for (int i = 0; i < d - n; i++) {
				std::cout << two;
			}
			break;
	case 0: for (int i = 0; i < d; i++) {
				std::cout << one;
			}
			for (int i = 0; i < n - d; i++) {
				std::cout << zero;
			}
			break;
  }
  std::cout << std::endl;
  return 0;
}