import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int A = scan.nextInt();
		int B = scan.nextInt();
		int C = scan.nextInt();
		int D = scan.nextInt();

		int X = (A + D - 1) / D;
		int Y = (C + B - 1) / B;
		if (X >= Y) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int A = scan.nextInt();
		int B = scan.nextInt();
		int C = scan.nextInt();
		int D = scan.nextInt();

		int X = (A + D - 1) / D;
		int Y = (C + B - 1) / B;
		if (X >= Y) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	}
} Main public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int A = scan.nextInt();
		int B = scan.nextInt();
		int C = scan.nextInt();
		int D = scan.nextInt();

		int X = (A + D - 1) / D;
		int Y = (C + B - 1) / B;
		if (X >= Y) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	} main {

		Scanner scan = new Scanner(System.in);

		int A = scan.nextInt();
		int B = scan.nextInt();
		int C = scan.nextInt();
		int D = scan.nextInt();

		int X = (A + D - 1) / D;
		int Y = (C + B - 1) / B;
		if (X >= Y) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int A = scan.nextInt(); A scan.nextInt() scan.nextInt scan int B = scan.nextInt(); B scan.nextInt() scan.nextInt scan int C = scan.nextInt(); C scan.nextInt() scan.nextInt scan int D = scan.nextInt(); D scan.nextInt() scan.nextInt scan int X = (A + D - 1) / D; X (A + D - 1) / D (A + D - 1) A + D A D 1 D int Y = (C + B - 1) / B; Y (C + B - 1) / B (C + B - 1) C + B C B 1 B if (X >= Y) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		} X >= Y X Y {
			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" String[] args args public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int A = scan.nextInt();
		int B = scan.nextInt();
		int C = scan.nextInt();
		int D = scan.nextInt();

		int X = (A + D - 1) / D;
		int Y = (C + B - 1) / B;
		if (X >= Y) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	}
} public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int A = scan.nextInt();
		int B = scan.nextInt();
		int C = scan.nextInt();
		int D = scan.nextInt();

		int X = (A + D - 1) / D;
		int Y = (C + B - 1) / B;
		if (X >= Y) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int A = scan.nextInt();
		int B = scan.nextInt();
		int C = scan.nextInt();
		int D = scan.nextInt();

		int X = (A + D - 1) / D;
		int Y = (C + B - 1) / B;
		if (X >= Y) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	}
}
