import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan =new Scanner(System.in);
		String S =scan.next();
		String T =scan.next();
		int result =T.indexOf(S);
		if(result==0&&S.length()+1==T.length()) {
			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) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan =new Scanner(System.in);
		String S =scan.next();
		String T =scan.next();
		int result =T.indexOf(S);
		if(result==0&&S.length()+1==T.length()) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	}

} Main public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan =new Scanner(System.in);
		String S =scan.next();
		String T =scan.next();
		int result =T.indexOf(S);
		if(result==0&&S.length()+1==T.length()) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	} main {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan =new Scanner(System.in);
		String S =scan.next();
		String T =scan.next();
		int result =T.indexOf(S);
		if(result==0&&S.length()+1==T.length()) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	} Scanner scan =new Scanner(System.in); scan new Scanner(System.in) String S =scan.next(); S scan.next() scan.next scan String T =scan.next(); T scan.next() scan.next scan int result =T.indexOf(S); result T.indexOf(S) T.indexOf T S if(result==0&&S.length()+1==T.length()) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		} result==0&&S.length()+1==T.length() result==0 result 0 S.length()+1==T.length() S.length()+1 S.length() S.length S 1 T.length() T.length T {
			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) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan =new Scanner(System.in);
		String S =scan.next();
		String T =scan.next();
		int result =T.indexOf(S);
		if(result==0&&S.length()+1==T.length()) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	}

} public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan =new Scanner(System.in);
		String S =scan.next();
		String T =scan.next();
		int result =T.indexOf(S);
		if(result==0&&S.length()+1==T.length()) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	}

} Main
import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan =new Scanner(System.in);
		String S =scan.next();
		String T =scan.next();
		int result =T.indexOf(S);
		if(result==0&&S.length()+1==T.length()) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	}

}
