import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String S = br.readLine();
	String T = br.readLine();
	if (T.length() == S.length() + 1 && T.substring(0, S.length()).equals(S)) {
	    System.out.println("Yes");
	} else {
	    System.out.println("No");
	}
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String S = br.readLine();
	String T = br.readLine();
	if (T.length() == S.length() + 1 && T.substring(0, S.length()).equals(S)) {
	    System.out.println("Yes");
	} else {
	    System.out.println("No");
	}
    }
} Main public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String S = br.readLine();
	String T = br.readLine();
	if (T.length() == S.length() + 1 && T.substring(0, S.length()).equals(S)) {
	    System.out.println("Yes");
	} else {
	    System.out.println("No");
	}
    } main {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String S = br.readLine();
	String T = br.readLine();
	if (T.length() == S.length() + 1 && T.substring(0, S.length()).equals(S)) {
	    System.out.println("Yes");
	} else {
	    System.out.println("No");
	}
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) String S = br.readLine(); S br.readLine() br.readLine br String T = br.readLine(); T br.readLine() br.readLine br if (T.length() == S.length() + 1 && T.substring(0, S.length()).equals(S)) {
	    System.out.println("Yes");
	} else {
	    System.out.println("No");
	} T.length() == S.length() + 1 && T.substring(0, S.length()).equals(S) T.length() == S.length() + 1 T.length() T.length T S.length() + 1 S.length() S.length S 1 T.substring(0, S.length()).equals(S) T.substring(0, S.length()).equals T.substring(0, S.length()) T.substring T 0 S.length() S.length S 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" String args[] args public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String S = br.readLine();
	String T = br.readLine();
	if (T.length() == S.length() + 1 && T.substring(0, S.length()).equals(S)) {
	    System.out.println("Yes");
	} else {
	    System.out.println("No");
	}
    }
} public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String S = br.readLine();
	String T = br.readLine();
	if (T.length() == S.length() + 1 && T.substring(0, S.length()).equals(S)) {
	    System.out.println("Yes");
	} else {
	    System.out.println("No");
	}
    }
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String S = br.readLine();
	String T = br.readLine();
	if (T.length() == S.length() + 1 && T.substring(0, S.length()).equals(S)) {
	    System.out.println("Yes");
	} else {
	    System.out.println("No");
	}
    }
}