#include<cstdio>
#include <iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<vector>
#include<functional>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<numeric>

#define mod (ll)(1e9+7);

using namespace std;
typedef long long ll;
typedef pair<ll, ll> Pr;

int N, D;

int main()
{
	int a_num = 0;
	int c_num = 0;
	int b_num = 0;
	cin >> N >> D;
	if (D - N < 0) {
		a_num = D;
		c_num = N - D;
	}
	else if(N*2 == D){
		b_num = N;
	}
	else {
		b_num = D - N;
		a_num = N - b_num;
	}
	
	for (int i = 0; i < a_num; i++)
		cout << "A";
	for (int i = 0; i < b_num; i++)
		cout << "B";
	for (int i = 0; i < c_num; i++)
		cout << "C";
	cout << endl;
	return	0;
}