import java.util.Scanner;

public class Main {

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

		if (Math.ceil(a / d) >= Math.ceil(c / b)) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();
	}

} import java.util.Scanner; Scanner java.util public class Main {

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

		if (Math.ceil(a / d) >= Math.ceil(c / b)) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();
	}

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

		if (Math.ceil(a / d) >= Math.ceil(c / b)) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

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

		if (Math.ceil(a / d) >= Math.ceil(c / b)) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double a = sc.nextInt(); a sc.nextInt() sc.nextInt sc double b = sc.nextInt(); b sc.nextInt() sc.nextInt sc double c = sc.nextInt(); c sc.nextInt() sc.nextInt sc double d = sc.nextInt(); d sc.nextInt() sc.nextInt sc if (Math.ceil(a / d) >= Math.ceil(c / b)) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		} Math.ceil(a / d) >= Math.ceil(c / b) Math.ceil(a / d) Math.ceil Math a / d a d Math.ceil(c / b) Math.ceil Math c / b c b {
			System.out.println("Yes");
		} System.out.println("Yes") System.out.println System.out System System.out "Yes" {
			System.out.println("No");
		} System.out.println("No") System.out.println System.out System System.out "No" sc.close() sc.close sc String[] args args public class Main {

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

		if (Math.ceil(a / d) >= Math.ceil(c / b)) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();
	}

} public class Main {

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

		if (Math.ceil(a / d) >= Math.ceil(c / b)) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();
	}

} Main
import java.util.Scanner;

public class Main {

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

		if (Math.ceil(a / d) >= Math.ceil(c / b)) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();
	}

}
