#include<bits/stdc++.h>
using namespace std;
using ll = long long;

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << endl

void print(char c, ll num){
    FOR(i, 0, num){
        cout << c;
    }
}

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

    // input
    ll N, D;
    cin >> N >> D;

    if(D>N){
        // Bを使わざるを得ない
        ll B_num = D-N;
        ll A_num = N - B_num;
        print('A', A_num);
        print('B', B_num);
        cout << endl;
        return 0;
    }
    else if(D==N){
        print('A', N);
        cout << endl;
    }
    else{
        ll A_num = D;
        ll C_num = N - A_num;
        print('A', A_num);
        print('C', C_num);
        cout << endl;
    }
    
    return 0;
}