package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var sc = bufio.NewScanner(os.Stdin)

func Scanner() string {
	sc.Scan()
	return sc.Text()
}
func main() {
	buf := make([]byte, 0)
	sc.Buffer(buf, 100000007)
	sc.Split(bufio.ScanWords)
	ha, _ := strconv.Atoi(Scanner())
	hb, _ := strconv.Atoi(Scanner())
	hc, _ := strconv.Atoi(Scanner())

	for i := 200; i >= 150; i-- {
		if i == ha {
			fmt.Println("A")
		}
		if i == hb {
			fmt.Println("B")
		}
		if i == hc {
			fmt.Println("C")
		}
	}
}