import java.util.*;
public class Main {
	public static void main(String arg[]) {
		Scanner sc = new Scanner(System.in);
		String s1 = sc.next();
		String s2 = sc.next();
 
		s2 = s2.substring(0, s2.length()-1);
		if(s1.equals(s2)) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}
	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz