// Zero or One
package Bronze_IV_4;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;
public class Ex13623 {
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
StringTokenizer st = new StringTokenizer(br.readLine());
int a = Integer.parseInt(st.nextToken());
int b = Integer.parseInt(st.nextToken());
int c = Integer.parseInt(st.nextToken());
if (a == b && b == c) {
System.out.println('*');
} else if (a == b) {
System.out.println('C');
} else if (a == c) {
System.out.println('B');
} else if (b == c) {
System.out.println('A');
}
}
}