#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>

#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>

#include <functional>
#include <cassert>

typedef long long ll;
using namespace std;

#define debug(x) cerr << #x << " = " << (x) << endl;


#define mod 1000000007 //1e9+7(prime number)
#define INF 1000000000 //1e9
#define LLINF 2000000000000000000LL //2e18
#define SIZE 100010

int main(){
  int n,d;

  cin >> n >> d;

  int r2 = max(0,d-n);
  int r1 = max(0,d - r2*2);
  int r0 = n - r1 - r2;
  
  for(int i=0;i<r1;i++){
    printf("A");
  }
  for(int i=0;i<r2;i++){
    printf("B");
  }
  for(int i=0;i<r0;i++){
    printf("C");
  }

  puts("");
  
  return 0;
}