import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		try(Scanner sc = new Scanner(System.in)) {

			int a = sc.nextInt();
			int b = sc.nextInt();
			int c = sc.nextInt();
			int d = sc.nextInt();
			
			int countT = c / b + (c % b > 0 ? 1 : 0);
			int countA = a / d + (a % d > 0 ? 1 : 0);
			
			System.out.println(countA < countT ? "No" : "Yes"); 

		}
	}

} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args){
		try(Scanner sc = new Scanner(System.in)) {

			int a = sc.nextInt();
			int b = sc.nextInt();
			int c = sc.nextInt();
			int d = sc.nextInt();
			
			int countT = c / b + (c % b > 0 ? 1 : 0);
			int countA = a / d + (a % d > 0 ? 1 : 0);
			
			System.out.println(countA < countT ? "No" : "Yes"); 

		}
	}

} Main public static void main(String[] args){
		try(Scanner sc = new Scanner(System.in)) {

			int a = sc.nextInt();
			int b = sc.nextInt();
			int c = sc.nextInt();
			int d = sc.nextInt();
			
			int countT = c / b + (c % b > 0 ? 1 : 0);
			int countA = a / d + (a % d > 0 ? 1 : 0);
			
			System.out.println(countA < countT ? "No" : "Yes"); 

		}
	} main {
		try(Scanner sc = new Scanner(System.in)) {

			int a = sc.nextInt();
			int b = sc.nextInt();
			int c = sc.nextInt();
			int d = sc.nextInt();
			
			int countT = c / b + (c % b > 0 ? 1 : 0);
			int countA = a / d + (a % d > 0 ? 1 : 0);
			
			System.out.println(countA < countT ? "No" : "Yes"); 

		}
	} try(Scanner sc = new Scanner(System.in)) {

			int a = sc.nextInt();
			int b = sc.nextInt();
			int c = sc.nextInt();
			int d = sc.nextInt();
			
			int countT = c / b + (c % b > 0 ? 1 : 0);
			int countA = a / d + (a % d > 0 ? 1 : 0);
			
			System.out.println(countA < countT ? "No" : "Yes"); 

		} {

			int a = sc.nextInt();
			int b = sc.nextInt();
			int c = sc.nextInt();
			int d = sc.nextInt();
			
			int countT = c / b + (c % b > 0 ? 1 : 0);
			int countA = a / d + (a % d > 0 ? 1 : 0);
			
			System.out.println(countA < countT ? "No" : "Yes"); 

		} Scanner sc = new Scanner(System.in) Scanner sc = new Scanner(System.in) 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 int countT = c / b + (c % b > 0 ? 1 : 0); countT c / b + (c % b > 0 ? 1 : 0) c / b c b (c % b > 0 ? 1 : 0) c % b > 0 c % b c b 0 1 0 int countA = a / d + (a % d > 0 ? 1 : 0); countA a / d + (a % d > 0 ? 1 : 0) a / d a d (a % d > 0 ? 1 : 0) a % d > 0 a % d a d 0 1 0 System.out.println(countA < countT ? "No" : "Yes") System.out.println System.out System System.out countA < countT ? "No" : "Yes" countA < countT countA countT "No" "Yes" String[] args args public class Main {
	public static void main(String[] args){
		try(Scanner sc = new Scanner(System.in)) {

			int a = sc.nextInt();
			int b = sc.nextInt();
			int c = sc.nextInt();
			int d = sc.nextInt();
			
			int countT = c / b + (c % b > 0 ? 1 : 0);
			int countA = a / d + (a % d > 0 ? 1 : 0);
			
			System.out.println(countA < countT ? "No" : "Yes"); 

		}
	}

} public class Main {
	public static void main(String[] args){
		try(Scanner sc = new Scanner(System.in)) {

			int a = sc.nextInt();
			int b = sc.nextInt();
			int c = sc.nextInt();
			int d = sc.nextInt();
			
			int countT = c / b + (c % b > 0 ? 1 : 0);
			int countA = a / d + (a % d > 0 ? 1 : 0);
			
			System.out.println(countA < countT ? "No" : "Yes"); 

		}
	}

} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		try(Scanner sc = new Scanner(System.in)) {

			int a = sc.nextInt();
			int b = sc.nextInt();
			int c = sc.nextInt();
			int d = sc.nextInt();
			
			int countT = c / b + (c % b > 0 ? 1 : 0);
			int countA = a / d + (a % d > 0 ? 1 : 0);
			
			System.out.println(countA < countT ? "No" : "Yes"); 

		}
	}

}