import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String []args) throws IOException {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String s = br.readLine();
        String t = br.readLine();
        t=t.substring(0,t.length()-1);
        if(s.equals(t))
            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