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();

		if(t.startsWith(s) && t.replaceFirst(s, "").length() == 1 ) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
		sc.close();
	}

} 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();

		if(t.startsWith(s) && t.replaceFirst(s, "").length() == 1 ) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
		sc.close();
	}

} Main public static void main(String[] args) {

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

		if(t.startsWith(s) && t.replaceFirst(s, "").length() == 1 ) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
		sc.close();
	} main {

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

		if(t.startsWith(s) && t.replaceFirst(s, "").length() == 1 ) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
		sc.close();
	} 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 if(t.startsWith(s) && t.replaceFirst(s, "").length() == 1 ) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		} t.startsWith(s) && t.replaceFirst(s, "").length() == 1 t.startsWith(s) t.startsWith t s t.replaceFirst(s, "").length() == 1 t.replaceFirst(s, "").length() t.replaceFirst(s, "").length t.replaceFirst(s, "") t.replaceFirst t s "" 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" sc.close() sc.close sc 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();

		if(t.startsWith(s) && t.replaceFirst(s, "").length() == 1 ) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
		sc.close();
	}

} public class Main {

	public static void main(String[] args) {

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

		if(t.startsWith(s) && t.replaceFirst(s, "").length() == 1 ) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
		sc.close();
	}

} 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();

		if(t.startsWith(s) && t.replaceFirst(s, "").length() == 1 ) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
		sc.close();
	}

}