#include <iostream>
using namespace std;

int main() {
    int N, D;
    cin >> N >> D;
    if (N > D) {
        for (int i = 0; i < D; ++i) cout << "A";
        for (int i = 0; i < N - D; ++i) cout << "C";
    }
    else {
        for (int i = 0; i < 2 * N - D; ++i) cout << "A";
        for (int i = 0; i < D - N; ++i) cout << "B";
    }
}