import java.util.Scanner;

public class Main{
	public static void main(String[] args)throws Exception {
		Scanner scan = new Scanner(System.in);
		
		int health1 = scan.nextInt();
		int attack1 = scan.nextInt();
		
		int health2 = scan.nextInt();
		int attack2 = scan.nextInt();
		
		String hantei = "";
		
		for(;;) {
			health2 -= attack1;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
			
			health1 -= attack2;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
		}
		System.out.println(hantei);
		
		scan.close();
	}
} import java.util.Scanner; Scanner java.util public class Main{
	public static void main(String[] args)throws Exception {
		Scanner scan = new Scanner(System.in);
		
		int health1 = scan.nextInt();
		int attack1 = scan.nextInt();
		
		int health2 = scan.nextInt();
		int attack2 = scan.nextInt();
		
		String hantei = "";
		
		for(;;) {
			health2 -= attack1;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
			
			health1 -= attack2;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
		}
		System.out.println(hantei);
		
		scan.close();
	}
} Main public static void main(String[] args)throws Exception {
		Scanner scan = new Scanner(System.in);
		
		int health1 = scan.nextInt();
		int attack1 = scan.nextInt();
		
		int health2 = scan.nextInt();
		int attack2 = scan.nextInt();
		
		String hantei = "";
		
		for(;;) {
			health2 -= attack1;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
			
			health1 -= attack2;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
		}
		System.out.println(hantei);
		
		scan.close();
	} main {
		Scanner scan = new Scanner(System.in);
		
		int health1 = scan.nextInt();
		int attack1 = scan.nextInt();
		
		int health2 = scan.nextInt();
		int attack2 = scan.nextInt();
		
		String hantei = "";
		
		for(;;) {
			health2 -= attack1;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
			
			health1 -= attack2;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
		}
		System.out.println(hantei);
		
		scan.close();
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int health1 = scan.nextInt(); health1 scan.nextInt() scan.nextInt scan int attack1 = scan.nextInt(); attack1 scan.nextInt() scan.nextInt scan int health2 = scan.nextInt(); health2 scan.nextInt() scan.nextInt scan int attack2 = scan.nextInt(); attack2 scan.nextInt() scan.nextInt scan String hantei = ""; hantei "" for(;;) {
			health2 -= attack1;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
			
			health1 -= attack2;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
		} ; {
			health2 -= attack1;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
			
			health1 -= attack2;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
		} {
			health2 -= attack1;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
			
			health1 -= attack2;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
		} health2 -= attack1 health2 attack1 if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			} health1 <= 0 || health2 <= 0 health1 <= 0 health1 0 health2 <= 0 health2 0 {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			} if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				} health1 <= 0 health1 0 {
					hantei = "No";
					break;
				} hantei = "No" hantei "No" break; if(health2 <= 0){
					hantei = "Yes";
					break;
				} health2 <= 0 health2 0 {
					hantei = "Yes";
					break;
				} hantei = "Yes" hantei "Yes" break; health1 -= attack2 health1 attack2 if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			} health1 <= 0 || health2 <= 0 health1 <= 0 health1 0 health2 <= 0 health2 0 {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			} if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				} health1 <= 0 health1 0 {
					hantei = "No";
					break;
				} hantei = "No" hantei "No" break; if(health2 <= 0){
					hantei = "Yes";
					break;
				} health2 <= 0 health2 0 {
					hantei = "Yes";
					break;
				} hantei = "Yes" hantei "Yes" break; System.out.println(hantei) System.out.println System.out System System.out hantei scan.close() scan.close scan String[] args args public class Main{
	public static void main(String[] args)throws Exception {
		Scanner scan = new Scanner(System.in);
		
		int health1 = scan.nextInt();
		int attack1 = scan.nextInt();
		
		int health2 = scan.nextInt();
		int attack2 = scan.nextInt();
		
		String hantei = "";
		
		for(;;) {
			health2 -= attack1;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
			
			health1 -= attack2;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
		}
		System.out.println(hantei);
		
		scan.close();
	}
} public class Main{
	public static void main(String[] args)throws Exception {
		Scanner scan = new Scanner(System.in);
		
		int health1 = scan.nextInt();
		int attack1 = scan.nextInt();
		
		int health2 = scan.nextInt();
		int attack2 = scan.nextInt();
		
		String hantei = "";
		
		for(;;) {
			health2 -= attack1;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
			
			health1 -= attack2;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
		}
		System.out.println(hantei);
		
		scan.close();
	}
} Main
import java.util.Scanner;

public class Main{
	public static void main(String[] args)throws Exception {
		Scanner scan = new Scanner(System.in);
		
		int health1 = scan.nextInt();
		int attack1 = scan.nextInt();
		
		int health2 = scan.nextInt();
		int attack2 = scan.nextInt();
		
		String hantei = "";
		
		for(;;) {
			health2 -= attack1;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
			
			health1 -= attack2;
			
			if(health1 <= 0 || health2 <= 0) {
				if(health1 <= 0) {
					hantei = "No";
					break;
				}else if(health2 <= 0){
					hantei = "Yes";
					break;
				}
			}
		}
		System.out.println(hantei);
		
		scan.close();
	}
}