import java.util.*;
import java.io.*;

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 turn = true;
        while(true){
            if(turn){
                C -= B;
                turn = false;
            }else{
                A -= D;
                turn = true;
            }
            if(C <= 0) {
                System.out.println("Yes");
                break;
            }
            if(A <= 0) {
                System.out.println("No");
                break;
            }
        }


    }
} import java.util.*; util.* java import java.io.*; io.* 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();

        boolean turn = true;
        while(true){
            if(turn){
                C -= B;
                turn = false;
            }else{
                A -= D;
                turn = true;
            }
            if(C <= 0) {
                System.out.println("Yes");
                break;
            }
            if(A <= 0) {
                System.out.println("No");
                break;
            }
        }


    }
} 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 turn = true;
        while(true){
            if(turn){
                C -= B;
                turn = false;
            }else{
                A -= D;
                turn = true;
            }
            if(C <= 0) {
                System.out.println("Yes");
                break;
            }
            if(A <= 0) {
                System.out.println("No");
                break;
            }
        }


    } main {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();

        boolean turn = true;
        while(true){
            if(turn){
                C -= B;
                turn = false;
            }else{
                A -= D;
                turn = true;
            }
            if(C <= 0) {
                System.out.println("Yes");
                break;
            }
            if(A <= 0) {
                System.out.println("No");
                break;
            }
        }


    } 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 turn = true; turn true while(true){
            if(turn){
                C -= B;
                turn = false;
            }else{
                A -= D;
                turn = true;
            }
            if(C <= 0) {
                System.out.println("Yes");
                break;
            }
            if(A <= 0) {
                System.out.println("No");
                break;
            }
        } true {
            if(turn){
                C -= B;
                turn = false;
            }else{
                A -= D;
                turn = true;
            }
            if(C <= 0) {
                System.out.println("Yes");
                break;
            }
            if(A <= 0) {
                System.out.println("No");
                break;
            }
        } if(turn){
                C -= B;
                turn = false;
            }else{
                A -= D;
                turn = true;
            } turn {
                C -= B;
                turn = false;
            } C -= B C B turn = false turn false {
                A -= D;
                turn = true;
            } A -= D A D turn = true turn true if(C <= 0) {
                System.out.println("Yes");
                break;
            } C <= 0 C 0 {
                System.out.println("Yes");
                break;
            } System.out.println("Yes") System.out.println System.out System System.out "Yes" break; if(A <= 0) {
                System.out.println("No");
                break;
            } A <= 0 A 0 {
                System.out.println("No");
                break;
            } System.out.println("No") System.out.println System.out System System.out "No" break; 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 turn = true;
        while(true){
            if(turn){
                C -= B;
                turn = false;
            }else{
                A -= D;
                turn = true;
            }
            if(C <= 0) {
                System.out.println("Yes");
                break;
            }
            if(A <= 0) {
                System.out.println("No");
                break;
            }
        }


    }
} 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 turn = true;
        while(true){
            if(turn){
                C -= B;
                turn = false;
            }else{
                A -= D;
                turn = true;
            }
            if(C <= 0) {
                System.out.println("Yes");
                break;
            }
            if(A <= 0) {
                System.out.println("No");
                break;
            }
        }


    }
} Main
import java.util.*;
import java.io.*;

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 turn = true;
        while(true){
            if(turn){
                C -= B;
                turn = false;
            }else{
                A -= D;
                turn = true;
            }
            if(C <= 0) {
                System.out.println("Yes");
                break;
            }
            if(A <= 0) {
                System.out.println("No");
                break;
            }
        }


    }
}