import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;

public class No00000570_Main {
	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	public static void main(String[] args) throws IOException {
		int a = Integer.parseInt(br.readLine());
		int b = Integer.parseInt(br.readLine());
		int c = Integer.parseInt(br.readLine());
		int[] t = {a, b, c};
		Arrays.sort(t);
		for(int i = 2; 0 <= i; i--) {
			if(t[i] == a) {
				System.out.println("A");
			} else if(t[i] == b) {
				System.out.println("B");
			} else if (t[i] == c) {
				System.out.println("C");
			}
		}
	}
}