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();

		double tturn = Math.ceil(c/b);
		double aturn = Math.ceil(a/d);

		if(tturn <= aturn) {
			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 sc = new Scanner(System.in);
		double a = sc.nextInt();
		double b = sc.nextInt();
		double c = sc.nextInt();
		double d = sc.nextInt();

		double tturn = Math.ceil(c/b);
		double aturn = Math.ceil(a/d);

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

		double tturn = Math.ceil(c/b);
		double aturn = Math.ceil(a/d);

		if(tturn <= aturn) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	} main {
		Scanner sc = new Scanner(System.in);
		double a = sc.nextInt();
		double b = sc.nextInt();
		double c = sc.nextInt();
		double d = sc.nextInt();

		double tturn = Math.ceil(c/b);
		double aturn = Math.ceil(a/d);

		if(tturn <= aturn) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
	} 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 double tturn = Math.ceil(c/b); tturn Math.ceil(c/b) Math.ceil Math c/b c b double aturn = Math.ceil(a/d); aturn Math.ceil(a/d) Math.ceil Math a/d a d if(tturn <= aturn) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		} tturn <= aturn tturn aturn {
			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 sc = new Scanner(System.in);
		double a = sc.nextInt();
		double b = sc.nextInt();
		double c = sc.nextInt();
		double d = sc.nextInt();

		double tturn = Math.ceil(c/b);
		double aturn = Math.ceil(a/d);

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

		double tturn = Math.ceil(c/b);
		double aturn = Math.ceil(a/d);

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

		double tturn = Math.ceil(c/b);
		double aturn = Math.ceil(a/d);

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