import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();
        
        while(true){
            if(c-b <= 0){
                System.out.println("Yes");
                break;
            }else{
                c -= b;
            }
            if(a-d <= 0){
                System.out.println("No");
                break;
            }else{
                a -= d;
            }
        }
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();
        
        while(true){
            if(c-b <= 0){
                System.out.println("Yes");
                break;
            }else{
                c -= b;
            }
            if(a-d <= 0){
                System.out.println("No");
                break;
            }else{
                a -= d;
            }
        }
    }
} Main public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();
        
        while(true){
            if(c-b <= 0){
                System.out.println("Yes");
                break;
            }else{
                c -= b;
            }
            if(a-d <= 0){
                System.out.println("No");
                break;
            }else{
                a -= d;
            }
        }
    } main {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();
        
        while(true){
            if(c-b <= 0){
                System.out.println("Yes");
                break;
            }else{
                c -= b;
            }
            if(a-d <= 0){
                System.out.println("No");
                break;
            }else{
                a -= d;
            }
        }
    } 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 while(true){
            if(c-b <= 0){
                System.out.println("Yes");
                break;
            }else{
                c -= b;
            }
            if(a-d <= 0){
                System.out.println("No");
                break;
            }else{
                a -= d;
            }
        } true {
            if(c-b <= 0){
                System.out.println("Yes");
                break;
            }else{
                c -= b;
            }
            if(a-d <= 0){
                System.out.println("No");
                break;
            }else{
                a -= d;
            }
        } if(c-b <= 0){
                System.out.println("Yes");
                break;
            }else{
                c -= b;
            } c-b <= 0 c-b c b 0 {
                System.out.println("Yes");
                break;
            } System.out.println("Yes") System.out.println System.out System System.out "Yes" break; {
                c -= b;
            } c -= b c b if(a-d <= 0){
                System.out.println("No");
                break;
            }else{
                a -= d;
            } a-d <= 0 a-d a d 0 {
                System.out.println("No");
                break;
            } System.out.println("No") System.out.println System.out System System.out "No" break; {
                a -= d;
            } a -= d a d String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();
        
        while(true){
            if(c-b <= 0){
                System.out.println("Yes");
                break;
            }else{
                c -= b;
            }
            if(a-d <= 0){
                System.out.println("No");
                break;
            }else{
                a -= d;
            }
        }
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();
        
        while(true){
            if(c-b <= 0){
                System.out.println("Yes");
                break;
            }else{
                c -= b;
            }
            if(a-d <= 0){
                System.out.println("No");
                break;
            }else{
                a -= d;
            }
        }
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();
        
        while(true){
            if(c-b <= 0){
                System.out.println("Yes");
                break;
            }else{
                c -= b;
            }
            if(a-d <= 0){
                System.out.println("No");
                break;
            }else{
                a -= d;
            }
        }
    }
}