import java.io.PrintWriter;
import java.util.*;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        PrintWriter out = new PrintWriter(System.out);
        String s = sc.next();
        String t = sc.next();
        if (s.equals(t.substring(0, t.length() - 1))) {
            out.println("Yes");
        }
        else {
            out.println("No");
        }
        out.flush();
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz