#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <deque>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>

#define p(s) cout<<(s)<<endl
#define REP(i,n,N) for(int i=n;i<N;i++)
#define RREP(i,n,N) for(int i=N-1;i>=n;i--)
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define F first
#define S second
typedef long long int ll;
using namespace std;
const int mod=1e9+7;

int N,D;
int numb;
int main(){
    cin>>N>>D;
    numb=max(D-N,0);
    REP(i,0,min(N,D)-numb){
        cout<<'A';
    }
    REP(i,0,numb){
        cout<<'B';
    }
    REP(i,0,N-min(N,D)){
        cout<<'C';
    }
    cout<<endl;

    return 0;
}