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();
    int X=T.length();
    String Z=T.substring(0,X-1);
    if(S.equals(Z)) {
    	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