

import java.util.Scanner;
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();
        int x = (b+c-1)/b;
        int y = (d+a-1)/d;
        if(x<=y){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    }
} import java.util.Scanner; Scanner java.util 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();
        int x = (b+c-1)/b;
        int y = (d+a-1)/d;
        if(x<=y){
            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();
        int x = (b+c-1)/b;
        int y = (d+a-1)/d;
        if(x<=y){
            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();
        int x = (b+c-1)/b;
        int y = (d+a-1)/d;
        if(x<=y){
            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 int x = (b+c-1)/b; x (b+c-1)/b (b+c-1) b+c b c 1 b int y = (d+a-1)/d; y (d+a-1)/d (d+a-1) d+a d a 1 d if(x<=y){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        } x<=y x y {
            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


import java.util.Scanner;
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();
        int x = (b+c-1)/b;
        int y = (d+a-1)/d;
        if(x<=y){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    }
}