import java.util.Scanner;
 
 
	public class Main{
	  public static void main(String[] args) {
		  
		  Scanner scanner = new Scanner(System.in);
		  
		    String S = scanner.next();
	 		String T = scanner.next();
	 		
		  if (T.length() == S.length()+1 && T.indexOf(S) == 0) {
			  System.out.println("Yes");
		  }
		  else{
			  System.out.println("No");
		  }
		  scanner.close();
	}
} import java.util.Scanner; Scanner java.util public class Main{
	  public static void main(String[] args) {
		  
		  Scanner scanner = new Scanner(System.in);
		  
		    String S = scanner.next();
	 		String T = scanner.next();
	 		
		  if (T.length() == S.length()+1 && T.indexOf(S) == 0) {
			  System.out.println("Yes");
		  }
		  else{
			  System.out.println("No");
		  }
		  scanner.close();
	}
} Main public static void main(String[] args) {
		  
		  Scanner scanner = new Scanner(System.in);
		  
		    String S = scanner.next();
	 		String T = scanner.next();
	 		
		  if (T.length() == S.length()+1 && T.indexOf(S) == 0) {
			  System.out.println("Yes");
		  }
		  else{
			  System.out.println("No");
		  }
		  scanner.close();
	} main {
		  
		  Scanner scanner = new Scanner(System.in);
		  
		    String S = scanner.next();
	 		String T = scanner.next();
	 		
		  if (T.length() == S.length()+1 && T.indexOf(S) == 0) {
			  System.out.println("Yes");
		  }
		  else{
			  System.out.println("No");
		  }
		  scanner.close();
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) String S = scanner.next(); S scanner.next() scanner.next scanner String T = scanner.next(); T scanner.next() scanner.next scanner if (T.length() == S.length()+1 && T.indexOf(S) == 0) {
			  System.out.println("Yes");
		  }
		  else{
			  System.out.println("No");
		  } T.length() == S.length()+1 && T.indexOf(S) == 0 T.length() == S.length()+1 T.length() T.length T S.length()+1 S.length() S.length S 1 T.indexOf(S) == 0 T.indexOf(S) T.indexOf T S 0 {
			  System.out.println("Yes");
		  } System.out.println("Yes") System.out.println System.out System System.out "Yes" {
			  System.out.println("No");
		  } System.out.println("No") System.out.println System.out System System.out "No" scanner.close() scanner.close scanner String[] args args public class Main{
	  public static void main(String[] args) {
		  
		  Scanner scanner = new Scanner(System.in);
		  
		    String S = scanner.next();
	 		String T = scanner.next();
	 		
		  if (T.length() == S.length()+1 && T.indexOf(S) == 0) {
			  System.out.println("Yes");
		  }
		  else{
			  System.out.println("No");
		  }
		  scanner.close();
	}
} public class Main{
	  public static void main(String[] args) {
		  
		  Scanner scanner = new Scanner(System.in);
		  
		    String S = scanner.next();
	 		String T = scanner.next();
	 		
		  if (T.length() == S.length()+1 && T.indexOf(S) == 0) {
			  System.out.println("Yes");
		  }
		  else{
			  System.out.println("No");
		  }
		  scanner.close();
	}
} Main
import java.util.Scanner;
 
 
	public class Main{
	  public static void main(String[] args) {
		  
		  Scanner scanner = new Scanner(System.in);
		  
		    String S = scanner.next();
	 		String T = scanner.next();
	 		
		  if (T.length() == S.length()+1 && T.indexOf(S) == 0) {
			  System.out.println("Yes");
		  }
		  else{
			  System.out.println("No");
		  }
		  scanner.close();
	}
}