import 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();
        sc.close();
        int tk = (c + b - 1) / b;
        int ao = (d + a - 1) / d;
        if(tk <= ao){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    }
} import java.util.*; util.* java 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();
        sc.close();
        int tk = (c + b - 1) / b;
        int ao = (d + a - 1) / d;
        if(tk <= ao){
            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();
        sc.close();
        int tk = (c + b - 1) / b;
        int ao = (d + a - 1) / d;
        if(tk <= ao){
            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();
        sc.close();
        int tk = (c + b - 1) / b;
        int ao = (d + a - 1) / d;
        if(tk <= ao){
            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 sc.close() sc.close sc int tk = (c + b - 1) / b; tk (c + b - 1) / b (c + b - 1) c + b c b 1 b int ao = (d + a - 1) / d; ao (d + a - 1) / d (d + a - 1) d + a d a 1 d if(tk <= ao){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        } tk <= ao tk ao {
            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);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();
        sc.close();
        int tk = (c + b - 1) / b;
        int ao = (d + a - 1) / d;
        if(tk <= ao){
            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();
        sc.close();
        int tk = (c + b - 1) / b;
        int ao = (d + a - 1) / d;
        if(tk <= ao){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    }
} Main
import 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();
        sc.close();
        int tk = (c + b - 1) / b;
        int ao = (d + a - 1) / d;
        if(tk <= ao){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    }
}