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(S.length() + 1 == T.length()) {
			
			String TS = T.substring(0,S.length());
			if(TS.equals (S)) {
				System.out.println("Yes");
			}else {
				System.out.println("No");
			}
			
		}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();
		if(S.length() + 1 == T.length()) {
			
			String TS = T.substring(0,S.length());
			if(TS.equals (S)) {
				System.out.println("Yes");
			}else {
				System.out.println("No");
			}
			
		}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();
		if(S.length() + 1 == T.length()) {
			
			String TS = T.substring(0,S.length());
			if(TS.equals (S)) {
				System.out.println("Yes");
			}else {
				System.out.println("No");
			}
			
		}else {
			System.out.println("No");
		}

} main {
		Scanner sc = new Scanner(System.in);
        String S = sc.nextLine();
        String T = sc.nextLine();
		if(S.length() + 1 == T.length()) {
			
			String TS = T.substring(0,S.length());
			if(TS.equals (S)) {
				System.out.println("Yes");
			}else {
				System.out.println("No");
			}
			
		}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 if(S.length() + 1 == T.length()) {
			
			String TS = T.substring(0,S.length());
			if(TS.equals (S)) {
				System.out.println("Yes");
			}else {
				System.out.println("No");
			}
			
		}else {
			System.out.println("No");
		} S.length() + 1 == T.length() S.length() + 1 S.length() S.length S 1 T.length() T.length T {
			
			String TS = T.substring(0,S.length());
			if(TS.equals (S)) {
				System.out.println("Yes");
			}else {
				System.out.println("No");
			}
			
		} String TS = T.substring(0,S.length()); TS T.substring(0,S.length()) T.substring T 0 S.length() S.length S if(TS.equals (S)) {
				System.out.println("Yes");
			}else {
				System.out.println("No");
			} TS.equals (S) TS.equals TS 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" {
			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();
		if(S.length() + 1 == T.length()) {
			
			String TS = T.substring(0,S.length());
			if(TS.equals (S)) {
				System.out.println("Yes");
			}else {
				System.out.println("No");
			}
			
		}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();
		if(S.length() + 1 == T.length()) {
			
			String TS = T.substring(0,S.length());
			if(TS.equals (S)) {
				System.out.println("Yes");
			}else {
				System.out.println("No");
			}
			
		}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();
		if(S.length() + 1 == T.length()) {
			
			String TS = T.substring(0,S.length());
			if(TS.equals (S)) {
				System.out.println("Yes");
			}else {
				System.out.println("No");
			}
			
		}else {
			System.out.println("No");
		}

}
}