import java.util.Scanner;
public class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    String str1=sc.nextLine();
    String str2=sc.nextLine();
    int m=str1.length();
    int n=str2.length();
    String new_str2=str2.substring(0,m);
    if(str1.equals(new_str2)){
      if(n==m+1){
          System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }else{
      System.out.println("No");
    }
  }
} import java.util.Scanner; Scanner java.util public class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    String str1=sc.nextLine();
    String str2=sc.nextLine();
    int m=str1.length();
    int n=str2.length();
    String new_str2=str2.substring(0,m);
    if(str1.equals(new_str2)){
      if(n==m+1){
          System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }else{
      System.out.println("No");
    }
  }
} Main public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    String str1=sc.nextLine();
    String str2=sc.nextLine();
    int m=str1.length();
    int n=str2.length();
    String new_str2=str2.substring(0,m);
    if(str1.equals(new_str2)){
      if(n==m+1){
          System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }else{
      System.out.println("No");
    }
  } main {
    Scanner sc=new Scanner(System.in);
    String str1=sc.nextLine();
    String str2=sc.nextLine();
    int m=str1.length();
    int n=str2.length();
    String new_str2=str2.substring(0,m);
    if(str1.equals(new_str2)){
      if(n==m+1){
          System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }else{
      System.out.println("No");
    }
  } Scanner sc=new Scanner(System.in); sc new Scanner(System.in) String str1=sc.nextLine(); str1 sc.nextLine() sc.nextLine sc String str2=sc.nextLine(); str2 sc.nextLine() sc.nextLine sc int m=str1.length(); m str1.length() str1.length str1 int n=str2.length(); n str2.length() str2.length str2 String new_str2=str2.substring(0,m); new_str2 str2.substring(0,m) str2.substring str2 0 m if(str1.equals(new_str2)){
      if(n==m+1){
          System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }else{
      System.out.println("No");
    } str1.equals(new_str2) str1.equals str1 new_str2 {
      if(n==m+1){
          System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    } if(n==m+1){
          System.out.println("Yes");
      }else{
        System.out.println("No");
      } n==m+1 n m+1 m 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" {
      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 str1=sc.nextLine();
    String str2=sc.nextLine();
    int m=str1.length();
    int n=str2.length();
    String new_str2=str2.substring(0,m);
    if(str1.equals(new_str2)){
      if(n==m+1){
          System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }else{
      System.out.println("No");
    }
  }
} public class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    String str1=sc.nextLine();
    String str2=sc.nextLine();
    int m=str1.length();
    int n=str2.length();
    String new_str2=str2.substring(0,m);
    if(str1.equals(new_str2)){
      if(n==m+1){
          System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }else{
      System.out.println("No");
    }
  }
} Main
import java.util.Scanner;
public class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    String str1=sc.nextLine();
    String str2=sc.nextLine();
    int m=str1.length();
    int n=str2.length();
    String new_str2=str2.substring(0,m);
    if(str1.equals(new_str2)){
      if(n==m+1){
          System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }else{
      System.out.println("No");
    }
  }
}
