import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        String S = s.next();
        String T = s.next();
        char[] sc = S.toCharArray();
        char[] tc = T.toCharArray();

        if((tc.length - sc.length) > 1) {
            System.out.println("No");
        }

        // char[] ns = new char[sc.length+1];

        for (int i = 0; i < tc.length; i++) {
            if(i < sc.length && sc[i] != tc[i]){
                System.out.println("No");
                break;
            }

            if(i == tc.length-1) {
                System.out.println("Yes");
            }
        }

    }
}
/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