import java.util.*;

class Main {
    public static void main(final String[] args) {
        final Scanner scan = new Scanner(System.in);
        int a = scan.nextInt(); // Takahasi HP
        final int b = scan.nextInt();
        int c = scan.nextInt(); // Aoki HP
        final int d = scan.nextInt();
        scan. close();
        
        while(true){
            c -= b;
            if(c <= 0){
                System.out.print("Yes"); 
                break;
            }
            a -= d;
            if(a <= 0){
                System.out.println("No");
                break;
            }
        }
    }
} import java.util.*; util.* java class Main {
    public static void main(final String[] args) {
        final Scanner scan = new Scanner(System.in);
        int a = scan.nextInt(); // Takahasi HP
        final int b = scan.nextInt();
        int c = scan.nextInt(); // Aoki HP
        final int d = scan.nextInt();
        scan. close();
        
        while(true){
            c -= b;
            if(c <= 0){
                System.out.print("Yes"); 
                break;
            }
            a -= d;
            if(a <= 0){
                System.out.println("No");
                break;
            }
        }
    }
} Main public static void main(final String[] args) {
        final Scanner scan = new Scanner(System.in);
        int a = scan.nextInt(); // Takahasi HP
        final int b = scan.nextInt();
        int c = scan.nextInt(); // Aoki HP
        final int d = scan.nextInt();
        scan. close();
        
        while(true){
            c -= b;
            if(c <= 0){
                System.out.print("Yes"); 
                break;
            }
            a -= d;
            if(a <= 0){
                System.out.println("No");
                break;
            }
        }
    } main {
        final Scanner scan = new Scanner(System.in);
        int a = scan.nextInt(); // Takahasi HP
        final int b = scan.nextInt();
        int c = scan.nextInt(); // Aoki HP
        final int d = scan.nextInt();
        scan. close();
        
        while(true){
            c -= b;
            if(c <= 0){
                System.out.print("Yes"); 
                break;
            }
            a -= d;
            if(a <= 0){
                System.out.println("No");
                break;
            }
        }
    } final Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int a = scan.nextInt(); a scan.nextInt() scan.nextInt scan final int b = scan.nextInt(); b scan.nextInt() scan.nextInt scan int c = scan.nextInt(); c scan.nextInt() scan.nextInt scan final int d = scan.nextInt(); d scan.nextInt() scan.nextInt scan scan. close() scan. close scan while(true){
            c -= b;
            if(c <= 0){
                System.out.print("Yes"); 
                break;
            }
            a -= d;
            if(a <= 0){
                System.out.println("No");
                break;
            }
        } true {
            c -= b;
            if(c <= 0){
                System.out.print("Yes"); 
                break;
            }
            a -= d;
            if(a <= 0){
                System.out.println("No");
                break;
            }
        } c -= b c b if(c <= 0){
                System.out.print("Yes"); 
                break;
            } c <= 0 c 0 {
                System.out.print("Yes"); 
                break;
            } System.out.print("Yes") System.out.print System.out System System.out "Yes" break; a -= d a d 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; final String[] args args
import java.util.*;

class Main {
    public static void main(final String[] args) {
        final Scanner scan = new Scanner(System.in);
        int a = scan.nextInt(); // Takahasi HP
        final int b = scan.nextInt();
        int c = scan.nextInt(); // Aoki HP
        final int d = scan.nextInt();
        scan. close();
        
        while(true){
            c -= b;
            if(c <= 0){
                System.out.print("Yes"); 
                break;
            }
            a -= d;
            if(a <= 0){
                System.out.println("No");
                break;
            }
        }
    }
}