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();

      if (S.length() != T.length()-1){
        System.out.println("No");
      } else {
        if (S.equals(T.substring(0, T.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 S = sc.next();
      String T = sc.next();

      if (S.length() != T.length()-1){
        System.out.println("No");
      } else {
        if (S.equals(T.substring(0, T.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 S = sc.next();
      String T = sc.next();

      if (S.length() != T.length()-1){
        System.out.println("No");
      } else {
        if (S.equals(T.substring(0, T.length()-1))){
          System.out.println("Yes");
        } else {
          System.out.println("No");
        }
      }
  } main {
      Scanner sc = new Scanner(System.in);
      String S = sc.next();
      String T = sc.next();

      if (S.length() != T.length()-1){
        System.out.println("No");
      } else {
        if (S.equals(T.substring(0, T.length()-1))){
          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 if (S.length() != T.length()-1){
        System.out.println("No");
      } else {
        if (S.equals(T.substring(0, T.length()-1))){
          System.out.println("Yes");
        } else {
          System.out.println("No");
        }
      } S.length() != T.length()-1 S.length() S.length S T.length()-1 T.length() T.length T 1 {
        System.out.println("No");
      } System.out.println("No") System.out.println System.out System System.out "No" {
        if (S.equals(T.substring(0, T.length()-1))){
          System.out.println("Yes");
        } else {
          System.out.println("No");
        }
      } if (S.equals(T.substring(0, T.length()-1))){
          System.out.println("Yes");
        } else {
          System.out.println("No");
        } S.equals(T.substring(0, T.length()-1)) S.equals S T.substring(0, T.length()-1) T.substring T 0 T.length()-1 T.length() T.length T 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 S = sc.next();
      String T = sc.next();

      if (S.length() != T.length()-1){
        System.out.println("No");
      } else {
        if (S.equals(T.substring(0, T.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 S = sc.next();
      String T = sc.next();

      if (S.length() != T.length()-1){
        System.out.println("No");
      } else {
        if (S.equals(T.substring(0, T.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 S = sc.next();
      String T = sc.next();

      if (S.length() != T.length()-1){
        System.out.println("No");
      } else {
        if (S.equals(T.substring(0, T.length()-1))){
          System.out.println("Yes");
        } else {
          System.out.println("No");
        }
      }
  }
}