import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int a,b,c,d;
        a = sc.nextInt();
        b = sc.nextInt();
        c = sc.nextInt();
        d = sc.nextInt();
        int tokillaoki = 0,tokilltaka = 0;

        while (a>0){
            a -= d;
            tokilltaka++;
        }
        while (c>0){
            c -= b;
            tokillaoki++;
        }
        if(tokillaoki<=tokilltaka){
            System.out.println("Yes");

        }else {
            System.out.println("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,b,c,d;
        a = sc.nextInt();
        b = sc.nextInt();
        c = sc.nextInt();
        d = sc.nextInt();
        int tokillaoki = 0,tokilltaka = 0;

        while (a>0){
            a -= d;
            tokilltaka++;
        }
        while (c>0){
            c -= b;
            tokillaoki++;
        }
        if(tokillaoki<=tokilltaka){
            System.out.println("Yes");

        }else {
            System.out.println("No");
        }


        }


    } Main public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int a,b,c,d;
        a = sc.nextInt();
        b = sc.nextInt();
        c = sc.nextInt();
        d = sc.nextInt();
        int tokillaoki = 0,tokilltaka = 0;

        while (a>0){
            a -= d;
            tokilltaka++;
        }
        while (c>0){
            c -= b;
            tokillaoki++;
        }
        if(tokillaoki<=tokilltaka){
            System.out.println("Yes");

        }else {
            System.out.println("No");
        }


        } main {

        Scanner sc = new Scanner(System.in);
        int a,b,c,d;
        a = sc.nextInt();
        b = sc.nextInt();
        c = sc.nextInt();
        d = sc.nextInt();
        int tokillaoki = 0,tokilltaka = 0;

        while (a>0){
            a -= d;
            tokilltaka++;
        }
        while (c>0){
            c -= b;
            tokillaoki++;
        }
        if(tokillaoki<=tokilltaka){
            System.out.println("Yes");

        }else {
            System.out.println("No");
        }


        } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a a b b c c d; d a = sc.nextInt() a sc.nextInt() sc.nextInt sc b = sc.nextInt() b sc.nextInt() sc.nextInt sc c = sc.nextInt() c sc.nextInt() sc.nextInt sc d = sc.nextInt() d sc.nextInt() sc.nextInt sc int tokillaoki = 0 tokillaoki 0 tokilltaka = 0; tokilltaka 0 while (a>0){
            a -= d;
            tokilltaka++;
        } a>0 a 0 {
            a -= d;
            tokilltaka++;
        } a -= d a d tokilltaka++ tokilltaka while (c>0){
            c -= b;
            tokillaoki++;
        } c>0 c 0 {
            c -= b;
            tokillaoki++;
        } c -= b c b tokillaoki++ tokillaoki if(tokillaoki<=tokilltaka){
            System.out.println("Yes");

        }else {
            System.out.println("No");
        } tokillaoki<=tokilltaka tokillaoki tokilltaka {
            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,b,c,d;
        a = sc.nextInt();
        b = sc.nextInt();
        c = sc.nextInt();
        d = sc.nextInt();
        int tokillaoki = 0,tokilltaka = 0;

        while (a>0){
            a -= d;
            tokilltaka++;
        }
        while (c>0){
            c -= b;
            tokillaoki++;
        }
        if(tokillaoki<=tokilltaka){
            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,b,c,d;
        a = sc.nextInt();
        b = sc.nextInt();
        c = sc.nextInt();
        d = sc.nextInt();
        int tokillaoki = 0,tokilltaka = 0;

        while (a>0){
            a -= d;
            tokilltaka++;
        }
        while (c>0){
            c -= b;
            tokillaoki++;
        }
        if(tokillaoki<=tokilltaka){
            System.out.println("Yes");

        }else {
            System.out.println("No");
        }


        }


    } Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int a,b,c,d;
        a = sc.nextInt();
        b = sc.nextInt();
        c = sc.nextInt();
        d = sc.nextInt();
        int tokillaoki = 0,tokilltaka = 0;

        while (a>0){
            a -= d;
            tokilltaka++;
        }
        while (c>0){
            c -= b;
            tokillaoki++;
        }
        if(tokillaoki<=tokilltaka){
            System.out.println("Yes");

        }else {
            System.out.println("No");
        }


        }


    }



