#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n, d;
  cin >> n >> d;
  string ans = "";
  int cnt = n;
  rep(_, n) ans += 'A';
  rep(i, d - n) ans[i] = 'B';
  rep(i, n - d) ans[i] = 'C';
  sort(ans.begin(), ans.end());
  cout << ans << '\n';
  return 0;
}