import java.util.*;

public class Main {
    public static void main(String[] args ) throws Exception {
        Scanner sc = new Scanner(System.in);
        String S = sc.next();
        String T = sc.next();

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

    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args ) throws Exception {
        Scanner sc = new Scanner(System.in);
        String S = sc.next();
        String T = sc.next();

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

    }
} Main public static void main(String[] args ) throws Exception {
        Scanner sc = new Scanner(System.in);
        String S = sc.next();
        String T = sc.next();

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

    } main {
        Scanner sc = new Scanner(System.in);
        String S = sc.next();
        String T = sc.next();

        String end = T.substring(S.length(),S.length()+1);
        if(T.equals(S+end)){
            System.out.println("Yes");
        } else {
            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 String end = T.substring(S.length(),S.length()+1); end T.substring(S.length(),S.length()+1) T.substring T S.length() S.length S S.length()+1 S.length() S.length S 1 if(T.equals(S+end)){
            System.out.println("Yes");
        } else {
            System.out.println("No");
        } T.equals(S+end) T.equals T S+end S end {
            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 ) throws Exception {
        Scanner sc = new Scanner(System.in);
        String S = sc.next();
        String T = sc.next();

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

    }
} public class Main {
    public static void main(String[] args ) throws Exception {
        Scanner sc = new Scanner(System.in);
        String S = sc.next();
        String T = sc.next();

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

    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args ) throws Exception {
        Scanner sc = new Scanner(System.in);
        String S = sc.next();
        String T = sc.next();

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

    }
}
