//package beg_164;
import java.util.*;
public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner s = new Scanner(System.in);
		String[] x = s.nextLine().split(" ");
		
		int a = Integer.parseInt(x[0]);
		int b = Integer.parseInt(x[1]);
		int c = Integer.parseInt(x[2]);
		int d = Integer.parseInt(x[3]);
		
		int diff1 = (int) a/d;
		if (a%d!=0) {
			diff1=diff1+1;
		}
		int diff2 = (int) c/b;
		if (c%b!=0) {
			diff2=diff2+1;
		}
		
		boolean g = diff1>=diff2;
		if (g) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}
	}

} import java.util.*; util.* java public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner s = new Scanner(System.in);
		String[] x = s.nextLine().split(" ");
		
		int a = Integer.parseInt(x[0]);
		int b = Integer.parseInt(x[1]);
		int c = Integer.parseInt(x[2]);
		int d = Integer.parseInt(x[3]);
		
		int diff1 = (int) a/d;
		if (a%d!=0) {
			diff1=diff1+1;
		}
		int diff2 = (int) c/b;
		if (c%b!=0) {
			diff2=diff2+1;
		}
		
		boolean g = diff1>=diff2;
		if (g) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}
	}

} Main public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner s = new Scanner(System.in);
		String[] x = s.nextLine().split(" ");
		
		int a = Integer.parseInt(x[0]);
		int b = Integer.parseInt(x[1]);
		int c = Integer.parseInt(x[2]);
		int d = Integer.parseInt(x[3]);
		
		int diff1 = (int) a/d;
		if (a%d!=0) {
			diff1=diff1+1;
		}
		int diff2 = (int) c/b;
		if (c%b!=0) {
			diff2=diff2+1;
		}
		
		boolean g = diff1>=diff2;
		if (g) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}
	} main {
		// TODO Auto-generated method stub
		Scanner s = new Scanner(System.in);
		String[] x = s.nextLine().split(" ");
		
		int a = Integer.parseInt(x[0]);
		int b = Integer.parseInt(x[1]);
		int c = Integer.parseInt(x[2]);
		int d = Integer.parseInt(x[3]);
		
		int diff1 = (int) a/d;
		if (a%d!=0) {
			diff1=diff1+1;
		}
		int diff2 = (int) c/b;
		if (c%b!=0) {
			diff2=diff2+1;
		}
		
		boolean g = diff1>=diff2;
		if (g) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}
	} Scanner s = new Scanner(System.in); s new Scanner(System.in) String[] x = s.nextLine().split(" "); x s.nextLine().split(" ") s.nextLine().split s.nextLine() s.nextLine s " " int a = Integer.parseInt(x[0]); a Integer.parseInt(x[0]) Integer.parseInt Integer x[0] x 0 int b = Integer.parseInt(x[1]); b Integer.parseInt(x[1]) Integer.parseInt Integer x[1] x 1 int c = Integer.parseInt(x[2]); c Integer.parseInt(x[2]) Integer.parseInt Integer x[2] x 2 int d = Integer.parseInt(x[3]); d Integer.parseInt(x[3]) Integer.parseInt Integer x[3] x 3 int diff1 = (int) a/d; diff1 (int) a/d (int) a d if (a%d!=0) {
			diff1=diff1+1;
		} a%d!=0 a%d a d 0 {
			diff1=diff1+1;
		} diff1=diff1+1 diff1 diff1+1 diff1 1 int diff2 = (int) c/b; diff2 (int) c/b (int) c b if (c%b!=0) {
			diff2=diff2+1;
		} c%b!=0 c%b c b 0 {
			diff2=diff2+1;
		} diff2=diff2+1 diff2 diff2+1 diff2 1 boolean g = diff1>=diff2; g diff1>=diff2 diff1 diff2 if (g) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		} g {
			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) {
		// TODO Auto-generated method stub
		Scanner s = new Scanner(System.in);
		String[] x = s.nextLine().split(" ");
		
		int a = Integer.parseInt(x[0]);
		int b = Integer.parseInt(x[1]);
		int c = Integer.parseInt(x[2]);
		int d = Integer.parseInt(x[3]);
		
		int diff1 = (int) a/d;
		if (a%d!=0) {
			diff1=diff1+1;
		}
		int diff2 = (int) c/b;
		if (c%b!=0) {
			diff2=diff2+1;
		}
		
		boolean g = diff1>=diff2;
		if (g) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}
	}

} public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner s = new Scanner(System.in);
		String[] x = s.nextLine().split(" ");
		
		int a = Integer.parseInt(x[0]);
		int b = Integer.parseInt(x[1]);
		int c = Integer.parseInt(x[2]);
		int d = Integer.parseInt(x[3]);
		
		int diff1 = (int) a/d;
		if (a%d!=0) {
			diff1=diff1+1;
		}
		int diff2 = (int) c/b;
		if (c%b!=0) {
			diff2=diff2+1;
		}
		
		boolean g = diff1>=diff2;
		if (g) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}
	}

} Main
//package beg_164;
import java.util.*;
public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner s = new Scanner(System.in);
		String[] x = s.nextLine().split(" ");
		
		int a = Integer.parseInt(x[0]);
		int b = Integer.parseInt(x[1]);
		int c = Integer.parseInt(x[2]);
		int d = Integer.parseInt(x[3]);
		
		int diff1 = (int) a/d;
		if (a%d!=0) {
			diff1=diff1+1;
		}
		int diff2 = (int) c/b;
		if (c%b!=0) {
			diff2=diff2+1;
		}
		
		boolean g = diff1>=diff2;
		if (g) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}
	}

}
