import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = sc.nextLong();
        long C = sc.nextLong();
        long D = sc.nextLong();
        sc.close();

        long i = 0;
        for (i = 1;; i++) {
            if (C - B * i <= 0 || A - D * i <= 0)
                break;
        }

        if (C - B * i <= 0) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    }
} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = sc.nextLong();
        long C = sc.nextLong();
        long D = sc.nextLong();
        sc.close();

        long i = 0;
        for (i = 1;; i++) {
            if (C - B * i <= 0 || A - D * i <= 0)
                break;
        }

        if (C - B * i <= 0) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = sc.nextLong();
        long C = sc.nextLong();
        long D = sc.nextLong();
        sc.close();

        long i = 0;
        for (i = 1;; i++) {
            if (C - B * i <= 0 || A - D * i <= 0)
                break;
        }

        if (C - B * i <= 0) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    } main {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = sc.nextLong();
        long C = sc.nextLong();
        long D = sc.nextLong();
        sc.close();

        long i = 0;
        for (i = 1;; i++) {
            if (C - B * i <= 0 || A - D * i <= 0)
                break;
        }

        if (C - B * i <= 0) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long A = sc.nextLong(); A sc.nextLong() sc.nextLong sc long B = sc.nextLong(); B sc.nextLong() sc.nextLong sc long C = sc.nextLong(); C sc.nextLong() sc.nextLong sc long D = sc.nextLong(); D sc.nextLong() sc.nextLong sc sc.close() sc.close sc long i = 0; i 0 for (i = 1;; i++) {
            if (C - B * i <= 0 || A - D * i <= 0)
                break;
        } i = 1; i = 1 i 1 i++ i++ i {
            if (C - B * i <= 0 || A - D * i <= 0)
                break;
        } {
            if (C - B * i <= 0 || A - D * i <= 0)
                break;
        } if (C - B * i <= 0 || A - D * i <= 0)
                break; C - B * i <= 0 || A - D * i <= 0 C - B * i <= 0 C - B * i C B * i B i 0 A - D * i <= 0 A - D * i A D * i D i 0 break; if (C - B * i <= 0) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        } C - B * i <= 0 C - B * i C B * i B i 0 {
            System.out.println("Yes");
        } System.out.println("Yes") System.out.println System.out System System.out "Yes" {
            System.out.println("No");
        } System.out.println("No") System.out.println System.out System System.out "No" String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = sc.nextLong();
        long C = sc.nextLong();
        long D = sc.nextLong();
        sc.close();

        long i = 0;
        for (i = 1;; i++) {
            if (C - B * i <= 0 || A - D * i <= 0)
                break;
        }

        if (C - B * i <= 0) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    }
} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = sc.nextLong();
        long C = sc.nextLong();
        long D = sc.nextLong();
        sc.close();

        long i = 0;
        for (i = 1;; i++) {
            if (C - B * i <= 0 || A - D * i <= 0)
                break;
        }

        if (C - B * i <= 0) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    }
} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = sc.nextLong();
        long C = sc.nextLong();
        long D = sc.nextLong();
        sc.close();

        long i = 0;
        for (i = 1;; i++) {
            if (C - B * i <= 0 || A - D * i <= 0)
                break;
        }

        if (C - B * i <= 0) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    }
}