import java.util.Scanner;
public class Main{
    public static void main(String[] args){
    Scanner input=new Scanner(System.in);
    String s=input.next();
    String t=input.next();
    String temp=t.substring(0,t.length()-1);
    if(temp.equals(s)){
    System.out.print("Yes");
    }else System.out.print("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