// 提出時に消す


import java.util.Scanner;

// 提出時にMainに変更する
public class Main {
    public static void main(String[] args) throws Exception {
        // System.out.println("Hello Java");
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        String t = sc.next();
        if (s.equals(t.substring(0, s.length())) && (t.length() - 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) throws Exception {
        // System.out.println("Hello Java");
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        String t = sc.next();
        if (s.equals(t.substring(0, s.length())) && (t.length() - s.length() == 1)) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
        sc.close();
    }
} Main public static void main(String[] args) throws Exception {
        // System.out.println("Hello Java");
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        String t = sc.next();
        if (s.equals(t.substring(0, s.length())) && (t.length() - s.length() == 1)) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
        sc.close();
    } main {
        // System.out.println("Hello Java");
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        String t = sc.next();
        if (s.equals(t.substring(0, s.length())) && (t.length() - 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.next(); s sc.next() sc.next sc String t = sc.next(); t sc.next() sc.next sc if (s.equals(t.substring(0, s.length())) && (t.length() - s.length() == 1)) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        } s.equals(t.substring(0, s.length())) && (t.length() - s.length() == 1) s.equals(t.substring(0, s.length())) s.equals s t.substring(0, s.length()) t.substring t 0 s.length() s.length s (t.length() - s.length() == 1) t.length() - s.length() t.length() t.length t s.length() s.length 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) throws Exception {
        // System.out.println("Hello Java");
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        String t = sc.next();
        if (s.equals(t.substring(0, s.length())) && (t.length() - s.length() == 1)) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
        sc.close();
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        // System.out.println("Hello Java");
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        String t = sc.next();
        if (s.equals(t.substring(0, s.length())) && (t.length() - s.length() == 1)) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
        sc.close();
    }
} Main
// 提出時に消す


import java.util.Scanner;

// 提出時にMainに変更する
public class Main {
    public static void main(String[] args) throws Exception {
        // System.out.println("Hello Java");
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        String t = sc.next();
        if (s.equals(t.substring(0, s.length())) && (t.length() - s.length() == 1)) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
        sc.close();
    }
}