/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

import java.util.Scanner;

/**
 *
 * @author HRIDOY
 */
public class main{

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        Scanner sc = new Scanner(System.in);
        int a,b;
        String s;
        s= sc.next();
        System.out.println(s);
        a=s.indexOf("AB");
        b=s.indexOf("BA");
        System.out.println(a+" "+b);
        if(a==(b+1) || b==(a+1)){
            System.out.println("NO");
        }else if(a== -1 && b== -1){
            System.out.println("NO");
        }
        else{
            System.out.println("YES");
        }
    }

}