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

using ll=long long;
#define int ll

#define FOR(i,a,b) for(int i=int(a);i<int(b);i++)
#define REP(i,b) FOR(i,0,b)

int read(){
	int i;
	scanf("%lld",&i);
	return i;
}

signed main(){
	// your code goes here
	int N=read(),D=read();
	int A=0,B=0,C=0;
	int dif=D-N;
	if(dif>=0) B=dif;
	else	C=-dif;
	
	A=D-2*B;
	
	REP(i,A) printf("A");
	REP(i,B) printf("B");
	REP(i,C) printf("C");
}