import java.util.*;
//import java.util.Arrays;

public class Main { //クラス名はMain
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      int a = Integer.parseInt(sc.next());
      int b = Integer.parseInt(sc.next());
      int c = Integer.parseInt(sc.next());
      int d = Integer.parseInt(sc.next());

      double x = (double)a/d;
      double y = (double)c/b;
      x = Math.ceil(x);
      y = Math.ceil(y);

      if(x>=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }
} import java.util.*; util.* java public class Main { //クラス名はMain
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      int a = Integer.parseInt(sc.next());
      int b = Integer.parseInt(sc.next());
      int c = Integer.parseInt(sc.next());
      int d = Integer.parseInt(sc.next());

      double x = (double)a/d;
      double y = (double)c/b;
      x = Math.ceil(x);
      y = Math.ceil(y);

      if(x>=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }
} Main public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      int a = Integer.parseInt(sc.next());
      int b = Integer.parseInt(sc.next());
      int c = Integer.parseInt(sc.next());
      int d = Integer.parseInt(sc.next());

      double x = (double)a/d;
      double y = (double)c/b;
      x = Math.ceil(x);
      y = Math.ceil(y);

      if(x>=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    } main {
      Scanner sc = new Scanner(System.in);
      int a = Integer.parseInt(sc.next());
      int b = Integer.parseInt(sc.next());
      int c = Integer.parseInt(sc.next());
      int d = Integer.parseInt(sc.next());

      double x = (double)a/d;
      double y = (double)c/b;
      x = Math.ceil(x);
      y = Math.ceil(y);

      if(x>=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = Integer.parseInt(sc.next()); a Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int b = Integer.parseInt(sc.next()); b Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int c = Integer.parseInt(sc.next()); c Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int d = Integer.parseInt(sc.next()); d Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc double x = (double)a/d; x (double)a/d (double)a d double y = (double)c/b; y (double)c/b (double)c b x = Math.ceil(x) x Math.ceil(x) Math.ceil Math x y = Math.ceil(y) y Math.ceil(y) Math.ceil Math y if(x>=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      } x>=y x y {
        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 { //クラス名はMain
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      int a = Integer.parseInt(sc.next());
      int b = Integer.parseInt(sc.next());
      int c = Integer.parseInt(sc.next());
      int d = Integer.parseInt(sc.next());

      double x = (double)a/d;
      double y = (double)c/b;
      x = Math.ceil(x);
      y = Math.ceil(y);

      if(x>=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }
} public class Main { //クラス名はMain
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      int a = Integer.parseInt(sc.next());
      int b = Integer.parseInt(sc.next());
      int c = Integer.parseInt(sc.next());
      int d = Integer.parseInt(sc.next());

      double x = (double)a/d;
      double y = (double)c/b;
      x = Math.ceil(x);
      y = Math.ceil(y);

      if(x>=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }
} Main
import java.util.*;
//import java.util.Arrays;

public class Main { //クラス名はMain
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      int a = Integer.parseInt(sc.next());
      int b = Integer.parseInt(sc.next());
      int c = Integer.parseInt(sc.next());
      int d = Integer.parseInt(sc.next());

      double x = (double)a/d;
      double y = (double)c/b;
      x = Math.ceil(x);
      y = Math.ceil(y);

      if(x>=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }
}
