public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		String line = "";
		StringBuilder out = new StringBuilder();
		while ((line = in.readLine()) != null && line.length() != 0) {
			int[] a = readInts(line);
			if(a[0]!=a[1] && a[0]!=a[2])
				out.append("A\n");
			else if(a[0]!=a[1] && a[1]!=a[2])
				out.append("B\n");
			else if(a[0]!=a[2] && a[1]!=a[2])
				out.append("C\n");
			else
				out.append("*\n");
		}
		System.out.print(out);
	}