// ------------------------------------
// Date:2018/ 4/ 1
// Problem:No.501 穴と文字列 / 0501.cpp
//
// ------------------------------------


#include <bits/stdc++.h>

using namespace std;

#define EACH(i,a) for (auto& i : a)
#define FOR(i,a,b) for(int i=(int)a;i<(int)b;++i)
#define RFOR(i,a,b) for(int i=(int)b-1;i>=(int)a;--i)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(a) (a).begin(),(a).end()
#define debug(x) cerr << #x << ":" << x << endl;
#define OK(ok) cout << (ok ? "Yes" : "No") << endl;
typedef long long ll;

void CINT(){}
template <class Head,class... Tail>
void CINT(Head&& head,Tail&&... tail) {
  cin >> head; CINT(move(tail)...);
}
#define CIN(...) int __VA_ARGS__;CINT(__VA_ARGS__)
#define LCIN(...) ll __VA_ARGS__;CINT(__VA_ARGS__)
#define SCIN(...) string __VA_ARGS__;CINT(__VA_ARGS__)

const int INF = 1e9 + 1;
const int MOD = 1e9 + 7;
const int MAX_N = 1e5 + 1;

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);

  string ans;
  CIN(N, D);

  /*
  if (D == 0) {
    ans = string(N, 'C');
  } else
    */
  {
    int bNum = max(0, D - N);
    int aNum = max(0, D - bNum * 2);
    ans = string(aNum, 'A');
    ans += string(bNum, 'B');
    // debug(aNum);
    // debug(bNum);
    ans += string(N - bNum - aNum, 'C');
  }

  cout << ans << endl;
  

  return 0;
}