import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int A = scan.nextInt();
    int B = scan.nextInt();
    int C = scan.nextInt();
    int D = scan.nextInt();
    scan.close();

    System.out.println((C-1)/B<=(A-1)/D ? "Yes" : "No");
  }
} import java.util.Scanner; Scanner java.util public class Main {
  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int A = scan.nextInt();
    int B = scan.nextInt();
    int C = scan.nextInt();
    int D = scan.nextInt();
    scan.close();

    System.out.println((C-1)/B<=(A-1)/D ? "Yes" : "No");
  }
} Main public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int A = scan.nextInt();
    int B = scan.nextInt();
    int C = scan.nextInt();
    int D = scan.nextInt();
    scan.close();

    System.out.println((C-1)/B<=(A-1)/D ? "Yes" : "No");
  } main {
    Scanner scan = new Scanner(System.in);
    int A = scan.nextInt();
    int B = scan.nextInt();
    int C = scan.nextInt();
    int D = scan.nextInt();
    scan.close();

    System.out.println((C-1)/B<=(A-1)/D ? "Yes" : "No");
  } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int A = scan.nextInt(); A scan.nextInt() scan.nextInt scan int B = scan.nextInt(); B scan.nextInt() scan.nextInt scan int C = scan.nextInt(); C scan.nextInt() scan.nextInt scan int D = scan.nextInt(); D scan.nextInt() scan.nextInt scan scan.close() scan.close scan System.out.println((C-1)/B<=(A-1)/D ? "Yes" : "No") System.out.println System.out System System.out (C-1)/B<=(A-1)/D ? "Yes" : "No" (C-1)/B<=(A-1)/D (C-1)/B (C-1) C 1 B (A-1)/D (A-1) A 1 D "Yes" "No" String[] args args public class Main {
  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int A = scan.nextInt();
    int B = scan.nextInt();
    int C = scan.nextInt();
    int D = scan.nextInt();
    scan.close();

    System.out.println((C-1)/B<=(A-1)/D ? "Yes" : "No");
  }
} public class Main {
  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int A = scan.nextInt();
    int B = scan.nextInt();
    int C = scan.nextInt();
    int D = scan.nextInt();
    scan.close();

    System.out.println((C-1)/B<=(A-1)/D ? "Yes" : "No");
  }
} Main
import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int A = scan.nextInt();
    int B = scan.nextInt();
    int C = scan.nextInt();
    int D = scan.nextInt();
    scan.close();

    System.out.println((C-1)/B<=(A-1)/D ? "Yes" : "No");
  }
}