import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		try (Scanner scanner = new Scanner(System.in)) {
			int a = scanner.nextInt(), b = scanner.nextInt();
			int c = scanner.nextInt(), d = scanner.nextInt();
			System.out.println(((c + b - 1) / b <= (a + d - 1) / d) ? "Yes" : "No");
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {

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

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

	public static void main(String[] args) {
		try (Scanner scanner = new Scanner(System.in)) {
			int a = scanner.nextInt(), b = scanner.nextInt();
			int c = scanner.nextInt(), d = scanner.nextInt();
			System.out.println(((c + b - 1) / b <= (a + d - 1) / d) ? "Yes" : "No");
		}
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		try (Scanner scanner = new Scanner(System.in)) {
			int a = scanner.nextInt(), b = scanner.nextInt();
			int c = scanner.nextInt(), d = scanner.nextInt();
			System.out.println(((c + b - 1) / b <= (a + d - 1) / d) ? "Yes" : "No");
		}
	}
}
