import java.util.Scanner;

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() + 1 == t.length() && s.length() >= 1 && s.length() <= 10 && t.substring(0, t.length()-1).equals(s) == true){
            System.out.println("Yes");
        }
        else{
            System.out.println("No");
        }
    }
} import java.util.Scanner; Scanner java.util 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() + 1 == t.length() && s.length() >= 1 && s.length() <= 10 && t.substring(0, t.length()-1).equals(s) == true){
            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() + 1 == t.length() && s.length() >= 1 && s.length() <= 10 && t.substring(0, t.length()-1).equals(s) == true){
            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() + 1 == t.length() && s.length() >= 1 && s.length() <= 10 && t.substring(0, t.length()-1).equals(s) == true){
            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() + 1 == t.length() && s.length() >= 1 && s.length() <= 10 && t.substring(0, t.length()-1).equals(s) == true){
            System.out.println("Yes");
        }
        else{
            System.out.println("No");
        } s.length() + 1 == t.length() && s.length() >= 1 && s.length() <= 10 && t.substring(0, t.length()-1).equals(s) == true s.length() <= 10 s.length() + 1 == t.length() && s.length() >= 1 && s.length() <= 10 && t.substring(0, t.length()-1).equals(s) == true s.length() + 1 == t.length() s.length() + 1 s.length() s.length s 1 t.length() t.length t s.length() >= 1 s.length() s.length s 1 s.length() <= 10 s.length() s.length s 10 t.substring(0, t.length()-1).equals(s) == true t.substring(0, t.length()-1).equals(s) t.substring(0, t.length()-1).equals t.substring(0, t.length()-1) t.substring t 0 t.length()-1 t.length() t.length t 1 s true {
            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
import java.util.Scanner;

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() + 1 == t.length() && s.length() >= 1 && s.length() <= 10 && t.substring(0, t.length()-1).equals(s) == true){
            System.out.println("Yes");
        }
        else{
            System.out.println("No");
        }
    }
}