import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		while(a > 0 || c > 0) {
			c -= b;
			if(c <= 0)
				break;
			a -= d;
		}
		if(a > 0)
			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);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		while(a > 0 || c > 0) {
			c -= b;
			if(c <= 0)
				break;
			a -= d;
		}
		if(a > 0)
			System.out.println("Yes");
		else
			System.out.println("No");
	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		while(a > 0 || c > 0) {
			c -= b;
			if(c <= 0)
				break;
			a -= d;
		}
		if(a > 0)
			System.out.println("Yes");
		else
			System.out.println("No");
	} main {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		while(a > 0 || c > 0) {
			c -= b;
			if(c <= 0)
				break;
			a -= d;
		}
		if(a > 0)
			System.out.println("Yes");
		else
			System.out.println("No");
	} 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 while(a > 0 || c > 0) {
			c -= b;
			if(c <= 0)
				break;
			a -= d;
		} a > 0 || c > 0 a > 0 a 0 c > 0 c 0 {
			c -= b;
			if(c <= 0)
				break;
			a -= d;
		} c -= b c b if(c <= 0)
				break; c <= 0 c 0 break; a -= d a d if(a > 0)
			System.out.println("Yes");
		else
			System.out.println("No"); a > 0 a 0 System.out.println("Yes") System.out.println System.out System System.out "Yes" 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);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		while(a > 0 || c > 0) {
			c -= b;
			if(c <= 0)
				break;
			a -= d;
		}
		if(a > 0)
			System.out.println("Yes");
		else
			System.out.println("No");
	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		while(a > 0 || c > 0) {
			c -= b;
			if(c <= 0)
				break;
			a -= d;
		}
		if(a > 0)
			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);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		while(a > 0 || c > 0) {
			c -= b;
			if(c <= 0)
				break;
			a -= d;
		}
		if(a > 0)
			System.out.println("Yes");
		else
			System.out.println("No");
	}

}
