package yukicoder;

import java.util.*;

public class No570 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        Integer[] h = new Integer[3];
        for(int i = 0; i < h.length; i++) {
            h[i] = sc.nextInt();
        }

        Integer[] h2 = h.clone();
        Arrays.sort(h, Comparator.reverseOrder());
        for(Integer i : h) {
            if(i == h2[0]) {
                System.out.println('A');
            } else if(i == h2[1]) {
                System.out.println('B');
            } else {
                System.out.println('C');
            }
        }
    }
}