import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		String s = sc.nextLine();
		String t = sc.nextLine();

		sc.close();


		if (s.equals(t.substring(0, t.length()-1)) &&
				t.matches(s + "[a-z]")) {
				//t.substring(t.length(), t.length()).matches("[a-z]")) {
			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.nextLine();
		String t = sc.nextLine();

		sc.close();


		if (s.equals(t.substring(0, t.length()-1)) &&
				t.matches(s + "[a-z]")) {
				//t.substring(t.length(), t.length()).matches("[a-z]")) {
			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.nextLine();
		String t = sc.nextLine();

		sc.close();


		if (s.equals(t.substring(0, t.length()-1)) &&
				t.matches(s + "[a-z]")) {
				//t.substring(t.length(), t.length()).matches("[a-z]")) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	} main {

		Scanner sc = new Scanner(System.in);
		String s = sc.nextLine();
		String t = sc.nextLine();

		sc.close();


		if (s.equals(t.substring(0, t.length()-1)) &&
				t.matches(s + "[a-z]")) {
				//t.substring(t.length(), t.length()).matches("[a-z]")) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String s = sc.nextLine(); s sc.nextLine() sc.nextLine sc String t = sc.nextLine(); t sc.nextLine() sc.nextLine sc sc.close() sc.close sc if (s.equals(t.substring(0, t.length()-1)) &&
				t.matches(s + "[a-z]")) {
				//t.substring(t.length(), t.length()).matches("[a-z]")) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		} s.equals(t.substring(0, t.length()-1)) &&
				t.matches(s + "[a-z]") 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 t.matches(s + "[a-z]") t.matches t s + "[a-z]" s "[a-z]" {
				//t.substring(t.length(), t.length()).matches("[a-z]")) {
			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.nextLine();
		String t = sc.nextLine();

		sc.close();


		if (s.equals(t.substring(0, t.length()-1)) &&
				t.matches(s + "[a-z]")) {
				//t.substring(t.length(), t.length()).matches("[a-z]")) {
			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.nextLine();
		String t = sc.nextLine();

		sc.close();


		if (s.equals(t.substring(0, t.length()-1)) &&
				t.matches(s + "[a-z]")) {
				//t.substring(t.length(), t.length()).matches("[a-z]")) {
			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.nextLine();
		String t = sc.nextLine();

		sc.close();


		if (s.equals(t.substring(0, t.length()-1)) &&
				t.matches(s + "[a-z]")) {
				//t.substring(t.length(), t.length()).matches("[a-z]")) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	}

}