import java.io.FileReader;
import java.math.BigInteger;
import java.util.Scanner;

public class EndOfWorld {

	private void work() throws Exception {
		Scanner sc = new Scanner(new FileReader("endofworld.in"));
		while (sc.hasNext()) {
			char[] s = sc.next().toCharArray();
			BigInteger res = BigInteger.ONE.shiftLeft(s.length).subtract(
					BigInteger.ONE);
			char lastPeg = 'B';
			for (int i = s.length - 1; i >= 0; i--) {
				if (s[i] == lastPeg) {
					// if the i_th disk is moved where it should be, we made 2^i moves
					res = res.subtract(BigInteger.ONE.shiftLeft(i));
				} else {
					// otherwise we have to move all the smaller pegs to the 'spare' before we move the i_th disk
					lastPeg = getLastPeg(s[i], lastPeg);
				}
			}
			System.out.println(res);
		}
	}

	private char getLastPeg(char a, char b) {
		// NOT a AND NOT b
		if (a == 'A')
			return b == 'B' ? 'C' : 'B';
		if (a == 'B')
			return b == 'A' ? 'C' : 'A';
		return b == 'A' ? 'B' : 'A';
	}

	public static void main(String[] args) throws Exception {
		new EndOfWorld().work();
	}

}