import 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.substring(0, S.length()).equals(T.substring(0, S.length()))
                && S.length() == T.length() - 1) {

            System.out.println("Yes");
            return;
        }

        System.out.println("No");
    }
} import java.util.*; util.* java 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.substring(0, S.length()).equals(T.substring(0, S.length()))
                && S.length() == T.length() - 1) {

            System.out.println("Yes");
            return;
        }

        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.substring(0, S.length()).equals(T.substring(0, S.length()))
                && S.length() == T.length() - 1) {

            System.out.println("Yes");
            return;
        }

        System.out.println("No");
    } main {
        Scanner sc = new Scanner(System.in);
        String S = sc.next();
        String T = sc.next();

        if (S.substring(0, S.length()).equals(T.substring(0, S.length()))
                && S.length() == T.length() - 1) {

            System.out.println("Yes");
            return;
        }

        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.substring(0, S.length()).equals(T.substring(0, S.length()))
                && S.length() == T.length() - 1) {

            System.out.println("Yes");
            return;
        } S.substring(0, S.length()).equals(T.substring(0, S.length()))
                && S.length() == T.length() - 1 S.substring(0, S.length()).equals(T.substring(0, S.length())) S.substring(0, S.length()).equals S.substring(0, S.length()) S.substring S 0 S.length() S.length S T.substring(0, S.length()) T.substring T 0 S.length() S.length S S.length() == T.length() - 1 S.length() S.length S T.length() - 1 T.length() T.length T 1 {

            System.out.println("Yes");
            return;
        } System.out.println("Yes") System.out.println System.out System System.out "Yes" return; 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.substring(0, S.length()).equals(T.substring(0, S.length()))
                && S.length() == T.length() - 1) {

            System.out.println("Yes");
            return;
        }

        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.substring(0, S.length()).equals(T.substring(0, S.length()))
                && S.length() == T.length() - 1) {

            System.out.println("Yes");
            return;
        }

        System.out.println("No");
    }
} Main
import 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.substring(0, S.length()).equals(T.substring(0, S.length()))
                && S.length() == T.length() - 1) {

            System.out.println("Yes");
            return;
        }

        System.out.println("No");
    }
}