#include<iostream>
#include<algorithm>
#include<vector>
#include<set>
#include<string>


int main() {
	int n, d;
	std::cin >> n >> d;
	std::string s;
	int a = 0, b = 0, c = 0;
	b = d / 2;
	if (d % 2 == 1) {
		a = 1;
	}
	c = n - a - b;
	while (c>1) {
		b--;
		c--;
		a += 2;
	}
	for (int i = 0; i < a; i++) {
		std::cout << "A";
	}
	for (int i = 0; i < b; i++) {
		std::cout << "B";
	}
	for (int i = 0; i < c; i++) {
		std::cout << "C";
	}
	std::cout << std::endl;
}