import java.util.*;
class Main
{
  public static void main(String args[])
  {
    Scanner sc=new Scanner(System.in);
    String x=sc.next();
    String y=sc.next();
    x+=y.charAt(y.length()-1);
    if(x.equals(y))
      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