import java.util.Scanner;

 


public class Main {
        public static void main(String[] args) {
         
          Scanner sc = new Scanner(System.in);
         
          String s = sc.next(); 
          String t = sc.next(); 
          
      
         String T1 = t.substring(s.length() - 0); 
 

           if(t.equals(s+T1)) 
           {
             System.out.println("Yes");
           }
        else{
           System.out.println("No");
            }
         }
      }
/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