import java.io.*;
public class Main {
public static void main (String[]args) {

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    try {
 String s = br.readLine();
 String t = br.readLine();
 if((t.substring(0,t.length()-1).equals(s))) {
    System.out.println("Yes");
 }
 else{
    System.out.println("No");
 }

    }catch (Exception e) {
       }
       }
   }
/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