#include<iostream>
#include<vector>
#include<string>
#include<assert.h>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
using namespace std;
int main(){
	int n,d;
	cin>>n>>d;
	assert(1<=n&&n<=50000);
	assert(0<=d&&d<=2*n);
	string out="";
	rep(i,n){
		if(d)out+="A",d--;
		else out+="C";
	}
	rep(i,n)if(d)out[n-i-1]='B',d--;
	cout<<out<<endl;
}