public class Main {
    static FastScanner scan = new FastScanner();
    static java.io.PrintWriter out = new java.io.PrintWriter(System.out);

    public static void main(String[] args) {
        String a = getLine()[0];
        String b = getLine()[0];
        if(a.length()+1 ==b.length() && b.contains(a) && a.toCharArray()[0] == b.toCharArray()[0] && a.toCharArray()[a.length()-1] == b.toCharArray()[a.length()-1]){
            puts("Yes");
        }else{
            puts("No");
        }
        
        //ここから下は消さない
        out.flush();
    }

    public static void puts(Object mes){
        out.println(mes);
    }

    public static long[] getLineLongs(){
        return java.util.stream.Stream.of(getLine()).mapToLong(Long::parseLong).toArray();
    }

    public static int[] getLineInts(){
        return java.util.stream.Stream.of(getLine()).mapToInt(Integer::parseInt).toArray();
    }

    public static String[] getLine(){
        String line = scan.next();
        String[] sp = line.split(" ");
        if(sp.length == 1){
            //System.out.println(line);
            return new String[]{line};
        }else{
            return sp;
        }
    }
}

class FastScanner {
    private final java.io.InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        }else{
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (java.io.IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
    private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;}
    private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}
    public boolean hasNext() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; return hasNextByte();}
    public String next() {
        if (!hasNext()) throw new java.util.NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong() {
        if (!hasNext()) throw new java.util.NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDouble() { return Double.parseDouble(next());}
}

Measured memory_bytes: 32660