import 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();
        if((c%b>0?c/b+1:c/b)<=(a%d>0?a/d+1:a/d)){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    }
} import java.util.*; util.* java 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();
        if((c%b>0?c/b+1:c/b)<=(a%d>0?a/d+1:a/d)){
            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();
        if((c%b>0?c/b+1:c/b)<=(a%d>0?a/d+1:a/d)){
            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();
        if((c%b>0?c/b+1:c/b)<=(a%d>0?a/d+1:a/d)){
            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 if((c%b>0?c/b+1:c/b)<=(a%d>0?a/d+1:a/d)){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        } (c%b>0?c/b+1:c/b)<=(a%d>0?a/d+1:a/d) (c%b>0?c/b+1:c/b) c%b>0 c%b c b 0 c/b+1 c/b c b 1 c/b c b (a%d>0?a/d+1:a/d) a%d>0 a%d a d 0 a/d+1 a/d a d 1 a/d a d {
            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.*;

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();
        if((c%b>0?c/b+1:c/b)<=(a%d>0?a/d+1:a/d)){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    }
}