import java.util.*;

public class Main{
    public static void main(String[] args){
	Scanner sc = new Scanner(System.in);
	String S = sc.next();
    String T = sc.next();
      boolean flag = false;
	if(T.startsWith(S)){
      if(T.length() == (S.length() + 1))
        flag = true;
    }
  if(flag)
    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 S = sc.next();
    String T = sc.next();
      boolean flag = false;
	if(T.startsWith(S)){
      if(T.length() == (S.length() + 1))
        flag = true;
    }
  if(flag)
    System.out.println("Yes");
  else
    System.out.println("No");
    }
      
      
} Main public static void main(String[] args){
	Scanner sc = new Scanner(System.in);
	String S = sc.next();
    String T = sc.next();
      boolean flag = false;
	if(T.startsWith(S)){
      if(T.length() == (S.length() + 1))
        flag = true;
    }
  if(flag)
    System.out.println("Yes");
  else
    System.out.println("No");
    } main {
	Scanner sc = new Scanner(System.in);
	String S = sc.next();
    String T = sc.next();
      boolean flag = false;
	if(T.startsWith(S)){
      if(T.length() == (S.length() + 1))
        flag = true;
    }
  if(flag)
    System.out.println("Yes");
  else
    System.out.println("No");
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String S = sc.next(); S sc.next() sc.next sc String T = sc.next(); T sc.next() sc.next sc boolean flag = false; flag false if(T.startsWith(S)){
      if(T.length() == (S.length() + 1))
        flag = true;
    } T.startsWith(S) T.startsWith T S {
      if(T.length() == (S.length() + 1))
        flag = true;
    } if(T.length() == (S.length() + 1))
        flag = true; T.length() == (S.length() + 1) T.length() T.length T (S.length() + 1) S.length() S.length S 1 flag = true flag true if(flag)
    System.out.println("Yes");
  else
    System.out.println("No"); flag System.out.println("Yes") System.out.println System.out System System.out "Yes" 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 S = sc.next();
    String T = sc.next();
      boolean flag = false;
	if(T.startsWith(S)){
      if(T.length() == (S.length() + 1))
        flag = true;
    }
  if(flag)
    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 S = sc.next();
    String T = sc.next();
      boolean flag = false;
	if(T.startsWith(S)){
      if(T.length() == (S.length() + 1))
        flag = true;
    }
  if(flag)
    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 S = sc.next();
    String T = sc.next();
      boolean flag = false;
	if(T.startsWith(S)){
      if(T.length() == (S.length() + 1))
        flag = true;
    }
  if(flag)
    System.out.println("Yes");
  else
    System.out.println("No");
    }
      
      
}