import java.util.*;
public class Main{
	public static void main(String[] args){
    
      Scanner sc = new Scanner(System.in);
      
      String a = sc.next();
      String n = sc.next();
      
      if (n.startsWith(a) && n.length() == a.length() + 1) {
      	System.out.println("Yes");
      } else {
      	System.out.println("No");      
      }
    }
} import java.util.*; util.* java public class Main{
	public static void main(String[] args){
    
      Scanner sc = new Scanner(System.in);
      
      String a = sc.next();
      String n = sc.next();
      
      if (n.startsWith(a) && n.length() == a.length() + 1) {
      	System.out.println("Yes");
      } else {
      	System.out.println("No");      
      }
    }
} Main public static void main(String[] args){
    
      Scanner sc = new Scanner(System.in);
      
      String a = sc.next();
      String n = sc.next();
      
      if (n.startsWith(a) && n.length() == a.length() + 1) {
      	System.out.println("Yes");
      } else {
      	System.out.println("No");      
      }
    } main {
    
      Scanner sc = new Scanner(System.in);
      
      String a = sc.next();
      String n = sc.next();
      
      if (n.startsWith(a) && n.length() == a.length() + 1) {
      	System.out.println("Yes");
      } else {
      	System.out.println("No");      
      }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String a = sc.next(); a sc.next() sc.next sc String n = sc.next(); n sc.next() sc.next sc if (n.startsWith(a) && n.length() == a.length() + 1) {
      	System.out.println("Yes");
      } else {
      	System.out.println("No");      
      } n.startsWith(a) && n.length() == a.length() + 1 n.startsWith(a) n.startsWith n a n.length() == a.length() + 1 n.length() n.length n a.length() + 1 a.length() a.length a 1 {
      	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" String[] args args public class Main{
	public static void main(String[] args){
    
      Scanner sc = new Scanner(System.in);
      
      String a = sc.next();
      String n = sc.next();
      
      if (n.startsWith(a) && n.length() == a.length() + 1) {
      	System.out.println("Yes");
      } else {
      	System.out.println("No");      
      }
    }
} public class Main{
	public static void main(String[] args){
    
      Scanner sc = new Scanner(System.in);
      
      String a = sc.next();
      String n = sc.next();
      
      if (n.startsWith(a) && n.length() == a.length() + 1) {
      	System.out.println("Yes");
      } else {
      	System.out.println("No");      
      }
    }
} Main
import java.util.*;
public class Main{
	public static void main(String[] args){
    
      Scanner sc = new Scanner(System.in);
      
      String a = sc.next();
      String n = sc.next();
      
      if (n.startsWith(a) && n.length() == a.length() + 1) {
      	System.out.println("Yes");
      } else {
      	System.out.println("No");      
      }
    }
}