
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		sc.close();

		String result = (a+(d-1))/d >= (c+(b-1))/b ? "Yes" : "No";

		System.out.println(result);

	}

} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		sc.close();

		String result = (a+(d-1))/d >= (c+(b-1))/b ? "Yes" : "No";

		System.out.println(result);

	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		sc.close();

		String result = (a+(d-1))/d >= (c+(b-1))/b ? "Yes" : "No";

		System.out.println(result);

	} main {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		sc.close();

		String result = (a+(d-1))/d >= (c+(b-1))/b ? "Yes" : "No";

		System.out.println(result);

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc int c = sc.nextInt(); c sc.nextInt() sc.nextInt sc int d = sc.nextInt(); d sc.nextInt() sc.nextInt sc sc.close() sc.close sc String result = (a+(d-1))/d >= (c+(b-1))/b ? "Yes" : "No"; result (a+(d-1))/d >= (c+(b-1))/b ? "Yes" : "No" (a+(d-1))/d >= (c+(b-1))/b (a+(d-1))/d (a+(d-1)) a (d-1) d 1 d (c+(b-1))/b (c+(b-1)) c (b-1) b 1 b "Yes" "No" System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		sc.close();

		String result = (a+(d-1))/d >= (c+(b-1))/b ? "Yes" : "No";

		System.out.println(result);

	}

} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		sc.close();

		String result = (a+(d-1))/d >= (c+(b-1))/b ? "Yes" : "No";

		System.out.println(result);

	}

} Main

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		sc.close();

		String result = (a+(d-1))/d >= (c+(b-1))/b ? "Yes" : "No";

		System.out.println(result);

	}

}
