import java.util.Scanner;

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();
        int tk = (int)Math.ceil(a/(double)d);
        int ao = (int)Math.ceil(c/(double)b);
        if (tk<ao)System.out.println("No");
        else System.out.println("Yes");
    }
} import java.util.Scanner; Scanner java.util 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();
        int tk = (int)Math.ceil(a/(double)d);
        int ao = (int)Math.ceil(c/(double)b);
        if (tk<ao)System.out.println("No");
        else System.out.println("Yes");
    }
} 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();
        int tk = (int)Math.ceil(a/(double)d);
        int ao = (int)Math.ceil(c/(double)b);
        if (tk<ao)System.out.println("No");
        else System.out.println("Yes");
    } main {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();
        int tk = (int)Math.ceil(a/(double)d);
        int ao = (int)Math.ceil(c/(double)b);
        if (tk<ao)System.out.println("No");
        else System.out.println("Yes");
    } 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 int tk = (int)Math.ceil(a/(double)d); tk (int)Math.ceil(a/(double)d) Math.ceil Math a/(double)d a (double)d int ao = (int)Math.ceil(c/(double)b); ao (int)Math.ceil(c/(double)b) Math.ceil Math c/(double)b c (double)b if (tk<ao)System.out.println("No");
        else System.out.println("Yes"); tk<ao tk ao System.out.println("No") System.out.println System.out System System.out "No" System.out.println("Yes") System.out.println System.out System System.out "Yes" 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();
        int tk = (int)Math.ceil(a/(double)d);
        int ao = (int)Math.ceil(c/(double)b);
        if (tk<ao)System.out.println("No");
        else System.out.println("Yes");
    }
} 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();
        int tk = (int)Math.ceil(a/(double)d);
        int ao = (int)Math.ceil(c/(double)b);
        if (tk<ao)System.out.println("No");
        else System.out.println("Yes");
    }
} Main
import java.util.Scanner;

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();
        int tk = (int)Math.ceil(a/(double)d);
        int ao = (int)Math.ceil(c/(double)b);
        if (tk<ao)System.out.println("No");
        else System.out.println("Yes");
    }
}
