#define _USE_MATH_DEFINES
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<string>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include<queue>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include <sstream>
#include<iomanip>

//#include<bits/stdc++.h>


using namespace std;

int main() {

	int a, b;
	cin >> a >> b;

	int x = a,y=b;
	string p;
	for (int i = 0; i < a; i++) {
		if (y == 0)p += 'C';
		else if ((a - i) * 2 == y) {
			p += 'B'; y -= 2;
		}
		else {
			p += 'A'; y--;
		}
		
	}
	sort(p.begin(), p.end());
	cout << p << endl;
	return 0;
}