import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    String line;
    line=sc.nextLine();
    String n=line;
    line=sc.nextLine();
    String m=line;
    if(n.equals(m.substring(0,m.length()-1))){
      System.out.println("yes");
    }else{
      System.out.println("no");
    }
  }
}