#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
using namespace std;

int main(void){
  int n, d;
  cin >> n >> d;
  int needb = d - n;
  string ans = "";
  if(needb <= 0){
    for(int i = 0; i < n; i++){
      if(d == 0) ans += "C";
      else {
	ans += "A";
	d--;
      }
    }
  }else{
    for(int i = 0; i < n - needb; i++) ans += "A";
    for(int i = 0; i < needb; i++) ans += "B";
  }
  cout << ans << endl;
  return 0;
}