import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author iavanish
 */
public class Main {

    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        FastReader in = new FastReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ARegistration solver = new ARegistration();
        solver.solve(1, in, out);
        out.close();
    }

    static class ARegistration {

        public void solve(int testNumber, FastReader in, PrintWriter out) {
            String s = in.next().trim();
            while (s.isEmpty()) {
                s = in.next().trim();
            }
            String t = in.next().trim();
            while (t.isEmpty()) {
                t = in.next().trim();
            }

            if (s.equals(t.substring(0, t.length() - 1))) {
                out.println("Yes");
            } else {
                out.println("No");
            }
        }

    }

    static class FastReader {

        private final int BUFFER_SIZE = 1 << 16;
        private final int STRING_BUFFER_SIZE = 10000000;
        private final InputStream inputStream;
        private final byte[] buffer;
        private int bufferPointer;
        private int bytesRead;

        public FastReader() {
            this.inputStream = new DataInputStream(System.in);
            this.buffer = new byte[BUFFER_SIZE];
            this.bufferPointer = bytesRead = 0;
        }

        public FastReader(InputStream inputStream) {
            this.inputStream = inputStream;
            this.buffer = new byte[BUFFER_SIZE];
            this.bufferPointer = bytesRead = 0;
        }

        public FastReader(String fileName) {
            try {
                this.inputStream = new DataInputStream(new FileInputStream(fileName));
                this.buffer = new byte[BUFFER_SIZE];
                this.bufferPointer = bytesRead = 0;
            } catch (FileNotFoundException e) {
                throw new RuntimeException(e);
            }
        }

        public String next() {
            byte[] buffer = new byte[STRING_BUFFER_SIZE];
            int count = 0;
            int c;
            while ((c = read()) != -1) {
                if (c == '\n') {
                    break;
                }
                buffer[count++] = (byte) c;
            }
            return new String(buffer, 0, count);
        }

        public void fillBuffer() {
            try {
                bytesRead = inputStream.read(buffer, bufferPointer = 0, BUFFER_SIZE);
                if (bytesRead == -1) {
                    buffer[0] = -1;
                }
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }

        public byte read() {
            if (bufferPointer == bytesRead) {
                fillBuffer();
            }
            return buffer[bufferPointer++];
        }

    }

}



Measured memory_bytes: 36268