import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int a = sc.nextInt(); //高橋体力
		int b = sc.nextInt(); //高橋攻撃力
		int c = sc.nextInt(); //青木体力
		int d = sc.nextInt(); //青木攻撃力

		double num1 = Math.ceil((double)a / d) + 1;
		double num2 = Math.ceil((double)c / b) + 1;

		if(num2 <= num1) {
			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);

		int a = sc.nextInt(); //高橋体力
		int b = sc.nextInt(); //高橋攻撃力
		int c = sc.nextInt(); //青木体力
		int d = sc.nextInt(); //青木攻撃力

		double num1 = Math.ceil((double)a / d) + 1;
		double num2 = Math.ceil((double)c / b) + 1;

		if(num2 <= num1) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();

	}

} Main public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int a = sc.nextInt(); //高橋体力
		int b = sc.nextInt(); //高橋攻撃力
		int c = sc.nextInt(); //青木体力
		int d = sc.nextInt(); //青木攻撃力

		double num1 = Math.ceil((double)a / d) + 1;
		double num2 = Math.ceil((double)c / b) + 1;

		if(num2 <= num1) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();

	} main {

		Scanner sc = new Scanner(System.in);

		int a = sc.nextInt(); //高橋体力
		int b = sc.nextInt(); //高橋攻撃力
		int c = sc.nextInt(); //青木体力
		int d = sc.nextInt(); //青木攻撃力

		double num1 = Math.ceil((double)a / d) + 1;
		double num2 = Math.ceil((double)c / b) + 1;

		if(num2 <= num1) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();

	} 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 double num1 = Math.ceil((double)a / d) + 1; num1 Math.ceil((double)a / d) + 1 Math.ceil((double)a / d) Math.ceil Math (double)a / d (double)a d 1 double num2 = Math.ceil((double)c / b) + 1; num2 Math.ceil((double)c / b) + 1 Math.ceil((double)c / b) Math.ceil Math (double)c / b (double)c b 1 if(num2 <= num1) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		} num2 <= num1 num2 num1 {
			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);

		int a = sc.nextInt(); //高橋体力
		int b = sc.nextInt(); //高橋攻撃力
		int c = sc.nextInt(); //青木体力
		int d = sc.nextInt(); //青木攻撃力

		double num1 = Math.ceil((double)a / d) + 1;
		double num2 = Math.ceil((double)c / b) + 1;

		if(num2 <= num1) {
			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);

		int a = sc.nextInt(); //高橋体力
		int b = sc.nextInt(); //高橋攻撃力
		int c = sc.nextInt(); //青木体力
		int d = sc.nextInt(); //青木攻撃力

		double num1 = Math.ceil((double)a / d) + 1;
		double num2 = Math.ceil((double)c / b) + 1;

		if(num2 <= num1) {
			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);

		int a = sc.nextInt(); //高橋体力
		int b = sc.nextInt(); //高橋攻撃力
		int c = sc.nextInt(); //青木体力
		int d = sc.nextInt(); //青木攻撃力

		double num1 = Math.ceil((double)a / d) + 1;
		double num2 = Math.ceil((double)c / b) + 1;

		if(num2 <= num1) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();

	}

}