import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();
    int[] h = {a, b, c};
    Arrays.sort(h);
    for(int i = 2; i >= 0; i--) {
      if(h[i] == a) System.out.println("A");
      if(h[i] == b) System.out.println("B");
      if(h[i] == c) System.out.println("C");
    }
  }
}