#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define llong long long

int main() {
    int n, d;
    cin >> n >> d;

    if(n >= d) {
        rep(i, d) cout << 'A';
        rep(i, n-d) cout << 'C';
        cout << "\n";
    } else {
        rep(i, 2*n-d) cout << 'A';
        rep(i, d-n) cout << 'B';
        cout << "\n";
    }
}