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

public class No570 {
	public static void main(String[] args) throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int[] brothers = new int[3];
		for(int i=0; i < 3; i++) brothers[i] = Integer.parseInt(br.readLine());
		Map<Integer, String> map = new HashMap<Integer, String>();
		map.put(brothers[0], "A");
		map.put(brothers[1], "B");
		map.put(brothers[2], "C");
		Arrays.sort(brothers);
		for(int i=2; i > -1; i--){
			System.out.println(map.get(brothers[i]));
		}
	}
}