#include <bits/stdc++.h>
using namespace std;
#define int long long
int n,d;
signed main() 
{
    //freopen(".in","r",stdin);
    //freopen(".out","w",stdout);
    cin>>n>>d;
    while(n--)
    {
        if(d!=0&&d/n<2)
        {
            cout<<'A';
            d--;
        }
        else if(d!=0&&d/n==2)
        {
            cout<<'B';
            d-=2;
        }
        else cout<<'C';
    }
    return 0;
}