#include<iostream>
#include<string>
#include<vector>

//A = 65

using namespace std;

int main(){
  double a,b,c;
  int n, d;
  cin >> n >> d;
  double lack = d - n;
  string res = "";
  if(lack > 0){
    b = lack;
    c = 0;
  }else if(lack < 0){
    c = -1*lack;
    b = 0;
  }
  a = n - b - c;
  for(int ia=0;ia<a;ia++){
    res += "A";
  }
  for(int ib=0;ib<b;ib++){
    res += "B";
  }
  for(int ic=0;ic<c;ic++){
    res += "C";
  }
  cout << res << endl;
  return 0;
}