import java.util.*; 
 
class Main{
public static void main(String[] args){
	Scanner sc=new Scanner(System.in);
		String k=sc.next();
        String l=sc.next();
  		String m=l.substring(0,l.length()-1);
    
 	if(k.equals(m)){
    		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