import java.util.Scanner;
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(); boolean ans = false;
        for (int i = 0; i <= 100; i++) {
            if (a - d * i > 0 && c - b * (i + 1) <= 0) ans = true;
        }
        System.out.println(ans ? "Yes" : "No");
    }




} import java.util.Scanner; Scanner 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(); boolean ans = false;
        for (int i = 0; i <= 100; i++) {
            if (a - d * i > 0 && c - b * (i + 1) <= 0) ans = true;
        }
        System.out.println(ans ? "Yes" : "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(); boolean ans = false;
        for (int i = 0; i <= 100; i++) {
            if (a - d * i > 0 && c - b * (i + 1) <= 0) ans = true;
        }
        System.out.println(ans ? "Yes" : "No");
    } main {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt(); int b = sc.nextInt(); int c = sc.nextInt(); int d = sc.nextInt(); boolean ans = false;
        for (int i = 0; i <= 100; i++) {
            if (a - d * i > 0 && c - b * (i + 1) <= 0) ans = true;
        }
        System.out.println(ans ? "Yes" : "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 boolean ans = false; ans false for (int i = 0; i <= 100; i++) {
            if (a - d * i > 0 && c - b * (i + 1) <= 0) ans = true;
        } int i = 0; int i = 0; i 0 i <= 100 i 100 i++ i++ i {
            if (a - d * i > 0 && c - b * (i + 1) <= 0) ans = true;
        } {
            if (a - d * i > 0 && c - b * (i + 1) <= 0) ans = true;
        } if (a - d * i > 0 && c - b * (i + 1) <= 0) ans = true; a - d * i > 0 && c - b * (i + 1) <= 0 a - d * i > 0 a - d * i a d * i d i 0 c - b * (i + 1) <= 0 c - b * (i + 1) c b * (i + 1) b (i + 1) i 1 0 ans = true ans true System.out.println(ans ? "Yes" : "No") System.out.println System.out System System.out ans ? "Yes" : "No" ans "Yes" "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(); boolean ans = false;
        for (int i = 0; i <= 100; i++) {
            if (a - d * i > 0 && c - b * (i + 1) <= 0) ans = true;
        }
        System.out.println(ans ? "Yes" : "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(); boolean ans = false;
        for (int i = 0; i <= 100; i++) {
            if (a - d * i > 0 && c - b * (i + 1) <= 0) ans = true;
        }
        System.out.println(ans ? "Yes" : "No");
    }




} Main
import java.util.Scanner;
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(); boolean ans = false;
        for (int i = 0; i <= 100; i++) {
            if (a - d * i > 0 && c - b * (i + 1) <= 0) ans = true;
        }
        System.out.println(ans ? "Yes" : "No");
    }




}