import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner a = new Scanner(System.in);		
		String S = a.next();
		String T = a.next();
		String str = S + "[a-z]";
		
		if(T.matches(S + "[a-z]")) {
			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