package main

import "fmt"

func main() {
	var family [999]rune
	var h int
	for i := 'A'; i <= 'C'; i++ {
		fmt.Scan(&h)
		family[h] = i
	}
	for i := 200; i > 100; i-- {
		if family[i] != 0 {
			fmt.Println(string(family[i]))
		}
	}
}