#include <bits/stdc++.h>
using namespace std;

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);  
	int n, d;
	cin >> n >> d;
	if(n >= d) {
		for(int i = 0; i < n; i++) {
			if(i < d) {
				cout << "A";
			}
			else {
				cout << "C";
			}
		}
		cout << endl;
	}
	else {
		int need = d - n;
		for(int i = 0; i < n; i++) {
			if(i < n - need) {
				cout << "A";
			}
			else {
				cout << "B";
			}
		}
		cout << endl;
	}
	return 0;	
}