import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] sa = br.readLine().split(" ");
		br.close();

		int c1 = sa[0].charAt(0) - 'A';
		int c2 = sa[1].charAt(0) - 'A';
		if (Math.abs(c1 - c2) == 1) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}
	}
}