package main

import . "fmt"

func main() {
	var n int64
	Scan(&n)
	var s string
	for n>1 {
		n--
		if n%2==0 {
			n/=2
			s="A"+s
		} else {
			n/=3
			s="B"+s
		}
	}
	Println(s)
}