/*
 *created by Kraken on 12-05-2020 at 15:29
 */
import java.util.*;
import java.io.*;

public class Main {

  public static void main(String[] args) {
    FastReader sc = new FastReader();
    String s = sc.next(), t = sc.next();
    if (t.substring(0, t.length() - 1).equals(s))
      System.out.println("Yes");
    else
      System.out.println("No");
  }

  static class FastReader {

    BufferedReader br;

    StringTokenizer st;

    public FastReader() {
      br = new BufferedReader(new InputStreamReader(System.in));
    }

    String next() {
      while (st == null || !st.hasMoreElements()) {
        try {
          st = new StringTokenizer(br.readLine());
        }
        catch (IOException e) {
          e.printStackTrace();
        }
      }
      return st.nextToken();
    }

    int nextInt() {
      return Integer.parseInt(next());
    }

    long nextLong() {
      return Long.parseLong(next());
    }

    double nextDouble() {
      return Double.parseDouble(next());
    }

    String nextLine() {
      String str = "";
      try {
        str = br.readLine();
      }
      catch (IOException e) {
        e.printStackTrace();
      }
      return str;
    }
  }
} import java.util.*; util.* java import java.io.*; io.* java public class Main {

  public static void main(String[] args) {
    FastReader sc = new FastReader();
    String s = sc.next(), t = sc.next();
    if (t.substring(0, t.length() - 1).equals(s))
      System.out.println("Yes");
    else
      System.out.println("No");
  }

  static class FastReader {

    BufferedReader br;

    StringTokenizer st;

    public FastReader() {
      br = new BufferedReader(new InputStreamReader(System.in));
    }

    String next() {
      while (st == null || !st.hasMoreElements()) {
        try {
          st = new StringTokenizer(br.readLine());
        }
        catch (IOException e) {
          e.printStackTrace();
        }
      }
      return st.nextToken();
    }

    int nextInt() {
      return Integer.parseInt(next());
    }

    long nextLong() {
      return Long.parseLong(next());
    }

    double nextDouble() {
      return Double.parseDouble(next());
    }

    String nextLine() {
      String str = "";
      try {
        str = br.readLine();
      }
      catch (IOException e) {
        e.printStackTrace();
      }
      return str;
    }
  }
} Main public static void main(String[] args) {
    FastReader sc = new FastReader();
    String s = sc.next(), t = sc.next();
    if (t.substring(0, t.length() - 1).equals(s))
      System.out.println("Yes");
    else
      System.out.println("No");
  } main {
    FastReader sc = new FastReader();
    String s = sc.next(), t = sc.next();
    if (t.substring(0, t.length() - 1).equals(s))
      System.out.println("Yes");
    else
      System.out.println("No");
  } FastReader sc = new FastReader(); sc new FastReader() String s = sc.next() s sc.next() sc.next sc t = sc.next(); t sc.next() sc.next sc if (t.substring(0, t.length() - 1).equals(s))
      System.out.println("Yes");
    else
      System.out.println("No"); t.substring(0, t.length() - 1).equals(s) t.substring(0, t.length() - 1).equals t.substring(0, t.length() - 1) t.substring t 0 t.length() - 1 t.length() t.length t 1 s System.out.println("Yes") System.out.println System.out System System.out "Yes" System.out.println("No") System.out.println System.out System System.out "No" String[] args args static class FastReader {

    BufferedReader br;

    StringTokenizer st;

    public FastReader() {
      br = new BufferedReader(new InputStreamReader(System.in));
    }

    String next() {
      while (st == null || !st.hasMoreElements()) {
        try {
          st = new StringTokenizer(br.readLine());
        }
        catch (IOException e) {
          e.printStackTrace();
        }
      }
      return st.nextToken();
    }

    int nextInt() {
      return Integer.parseInt(next());
    }

    long nextLong() {
      return Long.parseLong(next());
    }

    double nextDouble() {
      return Double.parseDouble(next());
    }

    String nextLine() {
      String str = "";
      try {
        str = br.readLine();
      }
      catch (IOException e) {
        e.printStackTrace();
      }
      return str;
    }
  } FastReader BufferedReader br; br StringTokenizer st; st public FastReader() {
      br = new BufferedReader(new InputStreamReader(System.in));
    } FastReader {
      br = new BufferedReader(new InputStreamReader(System.in));
    } br = new BufferedReader(new InputStreamReader(System.in)) br new BufferedReader(new InputStreamReader(System.in)) String next() {
      while (st == null || !st.hasMoreElements()) {
        try {
          st = new StringTokenizer(br.readLine());
        }
        catch (IOException e) {
          e.printStackTrace();
        }
      }
      return st.nextToken();
    } next {
      while (st == null || !st.hasMoreElements()) {
        try {
          st = new StringTokenizer(br.readLine());
        }
        catch (IOException e) {
          e.printStackTrace();
        }
      }
      return st.nextToken();
    } while (st == null || !st.hasMoreElements()) {
        try {
          st = new StringTokenizer(br.readLine());
        }
        catch (IOException e) {
          e.printStackTrace();
        }
      } st == null || !st.hasMoreElements() st == null st null !st.hasMoreElements() st.hasMoreElements() st.hasMoreElements st {
        try {
          st = new StringTokenizer(br.readLine());
        }
        catch (IOException e) {
          e.printStackTrace();
        }
      } try {
          st = new StringTokenizer(br.readLine());
        }
        catch (IOException e) {
          e.printStackTrace();
        } catch (IOException e) {
          e.printStackTrace();
        } IOException e {
          e.printStackTrace();
        } e.printStackTrace() e.printStackTrace e {
          st = new StringTokenizer(br.readLine());
        } st = new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken(); st.nextToken() st.nextToken st int nextInt() {
      return Integer.parseInt(next());
    } nextInt {
      return Integer.parseInt(next());
    } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next long nextLong() {
      return Long.parseLong(next());
    } nextLong {
      return Long.parseLong(next());
    } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next double nextDouble() {
      return Double.parseDouble(next());
    } nextDouble {
      return Double.parseDouble(next());
    } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next String nextLine() {
      String str = "";
      try {
        str = br.readLine();
      }
      catch (IOException e) {
        e.printStackTrace();
      }
      return str;
    } nextLine {
      String str = "";
      try {
        str = br.readLine();
      }
      catch (IOException e) {
        e.printStackTrace();
      }
      return str;
    } String str = ""; str "" try {
        str = br.readLine();
      }
      catch (IOException e) {
        e.printStackTrace();
      } catch (IOException e) {
        e.printStackTrace();
      } IOException e {
        e.printStackTrace();
      } e.printStackTrace() e.printStackTrace e {
        str = br.readLine();
      } str = br.readLine() str br.readLine() br.readLine br return str; str public class Main {

  public static void main(String[] args) {
    FastReader sc = new FastReader();
    String s = sc.next(), t = sc.next();
    if (t.substring(0, t.length() - 1).equals(s))
      System.out.println("Yes");
    else
      System.out.println("No");
  }

  static class FastReader {

    BufferedReader br;

    StringTokenizer st;

    public FastReader() {
      br = new BufferedReader(new InputStreamReader(System.in));
    }

    String next() {
      while (st == null || !st.hasMoreElements()) {
        try {
          st = new StringTokenizer(br.readLine());
        }
        catch (IOException e) {
          e.printStackTrace();
        }
      }
      return st.nextToken();
    }

    int nextInt() {
      return Integer.parseInt(next());
    }

    long nextLong() {
      return Long.parseLong(next());
    }

    double nextDouble() {
      return Double.parseDouble(next());
    }

    String nextLine() {
      String str = "";
      try {
        str = br.readLine();
      }
      catch (IOException e) {
        e.printStackTrace();
      }
      return str;
    }
  }
} public class Main {

  public static void main(String[] args) {
    FastReader sc = new FastReader();
    String s = sc.next(), t = sc.next();
    if (t.substring(0, t.length() - 1).equals(s))
      System.out.println("Yes");
    else
      System.out.println("No");
  }

  static class FastReader {

    BufferedReader br;

    StringTokenizer st;

    public FastReader() {
      br = new BufferedReader(new InputStreamReader(System.in));
    }

    String next() {
      while (st == null || !st.hasMoreElements()) {
        try {
          st = new StringTokenizer(br.readLine());
        }
        catch (IOException e) {
          e.printStackTrace();
        }
      }
      return st.nextToken();
    }

    int nextInt() {
      return Integer.parseInt(next());
    }

    long nextLong() {
      return Long.parseLong(next());
    }

    double nextDouble() {
      return Double.parseDouble(next());
    }

    String nextLine() {
      String str = "";
      try {
        str = br.readLine();
      }
      catch (IOException e) {
        e.printStackTrace();
      }
      return str;
    }
  }
} Main
/*
 *created by Kraken on 12-05-2020 at 15:29
 */
import java.util.*;
import java.io.*;

public class Main {

  public static void main(String[] args) {
    FastReader sc = new FastReader();
    String s = sc.next(), t = sc.next();
    if (t.substring(0, t.length() - 1).equals(s))
      System.out.println("Yes");
    else
      System.out.println("No");
  }

  static class FastReader {

    BufferedReader br;

    StringTokenizer st;

    public FastReader() {
      br = new BufferedReader(new InputStreamReader(System.in));
    }

    String next() {
      while (st == null || !st.hasMoreElements()) {
        try {
          st = new StringTokenizer(br.readLine());
        }
        catch (IOException e) {
          e.printStackTrace();
        }
      }
      return st.nextToken();
    }

    int nextInt() {
      return Integer.parseInt(next());
    }

    long nextLong() {
      return Long.parseLong(next());
    }

    double nextDouble() {
      return Double.parseDouble(next());
    }

    String nextLine() {
      String str = "";
      try {
        str = br.readLine();
      }
      catch (IOException e) {
        e.printStackTrace();
      }
      return str;
    }
  }
}
