import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ

		Scanner sc=new Scanner(System.in);
		String S=sc.next();
		String T=sc.next();
		char toridasi=T.charAt(T.length()-1);
		String tasi=S+toridasi;
		
		
		if(T.equals(tasi)) {
			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