import java.util.Scanner;

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() + 1 == t.length() && t.startsWith(s)) {
            System.out.println("Yes");
        } 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 s = sc.next();
        String t = sc.next();
        if (s.length() + 1 == t.length() && t.startsWith(s)) {
            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() && t.startsWith(s)) {
            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() && t.startsWith(s)) {
            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() && t.startsWith(s)) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        } s.length() + 1 == t.length() && t.startsWith(s) s.length() + 1 == t.length() s.length() + 1 s.length() s.length s 1 t.length() t.length t t.startsWith(s) t.startsWith t s {
            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() + 1 == t.length() && t.startsWith(s)) {
            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() + 1 == t.length() && t.startsWith(s)) {
            System.out.println("Yes");
        } 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 s = sc.next();
        String t = sc.next();
        if (s.length() + 1 == t.length() && t.startsWith(s)) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    }

}
