import java.util.*;
 
public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int thp = sc.nextInt();
        int tat = sc.nextInt();
        int ahp = sc.nextInt();
        int aat = sc.nextInt();
        for(int i = 0; i < 100; i++){
        	ahp -= tat;
            if(ahp <= 0){
            	System.out.println("Yes");
                break;
            }
            thp -= aat;
            if(thp <= 0){
            	System.out.println("No");
                break;
            }
            
        }
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int thp = sc.nextInt();
        int tat = sc.nextInt();
        int ahp = sc.nextInt();
        int aat = sc.nextInt();
        for(int i = 0; i < 100; i++){
        	ahp -= tat;
            if(ahp <= 0){
            	System.out.println("Yes");
                break;
            }
            thp -= aat;
            if(thp <= 0){
            	System.out.println("No");
                break;
            }
            
        }
    }
} Main public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int thp = sc.nextInt();
        int tat = sc.nextInt();
        int ahp = sc.nextInt();
        int aat = sc.nextInt();
        for(int i = 0; i < 100; i++){
        	ahp -= tat;
            if(ahp <= 0){
            	System.out.println("Yes");
                break;
            }
            thp -= aat;
            if(thp <= 0){
            	System.out.println("No");
                break;
            }
            
        }
    } main {
        Scanner sc = new Scanner(System.in);
        int thp = sc.nextInt();
        int tat = sc.nextInt();
        int ahp = sc.nextInt();
        int aat = sc.nextInt();
        for(int i = 0; i < 100; i++){
        	ahp -= tat;
            if(ahp <= 0){
            	System.out.println("Yes");
                break;
            }
            thp -= aat;
            if(thp <= 0){
            	System.out.println("No");
                break;
            }
            
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int thp = sc.nextInt(); thp sc.nextInt() sc.nextInt sc int tat = sc.nextInt(); tat sc.nextInt() sc.nextInt sc int ahp = sc.nextInt(); ahp sc.nextInt() sc.nextInt sc int aat = sc.nextInt(); aat sc.nextInt() sc.nextInt sc for(int i = 0; i < 100; i++){
        	ahp -= tat;
            if(ahp <= 0){
            	System.out.println("Yes");
                break;
            }
            thp -= aat;
            if(thp <= 0){
            	System.out.println("No");
                break;
            }
            
        } int i = 0; int i = 0; i 0 i < 100 i 100 i++ i++ i {
        	ahp -= tat;
            if(ahp <= 0){
            	System.out.println("Yes");
                break;
            }
            thp -= aat;
            if(thp <= 0){
            	System.out.println("No");
                break;
            }
            
        } {
        	ahp -= tat;
            if(ahp <= 0){
            	System.out.println("Yes");
                break;
            }
            thp -= aat;
            if(thp <= 0){
            	System.out.println("No");
                break;
            }
            
        } ahp -= tat ahp tat if(ahp <= 0){
            	System.out.println("Yes");
                break;
            } ahp <= 0 ahp 0 {
            	System.out.println("Yes");
                break;
            } System.out.println("Yes") System.out.println System.out System System.out "Yes" break; thp -= aat thp aat if(thp <= 0){
            	System.out.println("No");
                break;
            } thp <= 0 thp 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) throws Exception {
        Scanner sc = new Scanner(System.in);
        int thp = sc.nextInt();
        int tat = sc.nextInt();
        int ahp = sc.nextInt();
        int aat = sc.nextInt();
        for(int i = 0; i < 100; i++){
        	ahp -= tat;
            if(ahp <= 0){
            	System.out.println("Yes");
                break;
            }
            thp -= aat;
            if(thp <= 0){
            	System.out.println("No");
                break;
            }
            
        }
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int thp = sc.nextInt();
        int tat = sc.nextInt();
        int ahp = sc.nextInt();
        int aat = sc.nextInt();
        for(int i = 0; i < 100; i++){
        	ahp -= tat;
            if(ahp <= 0){
            	System.out.println("Yes");
                break;
            }
            thp -= aat;
            if(thp <= 0){
            	System.out.println("No");
                break;
            }
            
        }
    }
} Main
import java.util.*;
 
public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int thp = sc.nextInt();
        int tat = sc.nextInt();
        int ahp = sc.nextInt();
        int aat = sc.nextInt();
        for(int i = 0; i < 100; i++){
        	ahp -= tat;
            if(ahp <= 0){
            	System.out.println("Yes");
                break;
            }
            thp -= aat;
            if(thp <= 0){
            	System.out.println("No");
                break;
            }
            
        }
    }
}