import java.util.*;

public class Main {
	public static void main(String[] args){
	Scanner scn = new Scanner(System.in);
	int a = scn.nextInt();
      int b = scn.nextInt();
      int c = scn.nextInt();
      int d = scn.nextInt();
      int x = c/b;
      int y = a/d;
      int xx = c%b;
      int yy = a%d;
      if(xx != 0){
        x = x+1;
      }
      if(yy != 0){
        y = y+1;
      }
      if(x<=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
	Scanner scn = new Scanner(System.in);
	int a = scn.nextInt();
      int b = scn.nextInt();
      int c = scn.nextInt();
      int d = scn.nextInt();
      int x = c/b;
      int y = a/d;
      int xx = c%b;
      int yy = a%d;
      if(xx != 0){
        x = x+1;
      }
      if(yy != 0){
        y = y+1;
      }
      if(x<=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
	}
} Main public static void main(String[] args){
	Scanner scn = new Scanner(System.in);
	int a = scn.nextInt();
      int b = scn.nextInt();
      int c = scn.nextInt();
      int d = scn.nextInt();
      int x = c/b;
      int y = a/d;
      int xx = c%b;
      int yy = a%d;
      if(xx != 0){
        x = x+1;
      }
      if(yy != 0){
        y = y+1;
      }
      if(x<=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
	} main {
	Scanner scn = new Scanner(System.in);
	int a = scn.nextInt();
      int b = scn.nextInt();
      int c = scn.nextInt();
      int d = scn.nextInt();
      int x = c/b;
      int y = a/d;
      int xx = c%b;
      int yy = a%d;
      if(xx != 0){
        x = x+1;
      }
      if(yy != 0){
        y = y+1;
      }
      if(x<=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
	} Scanner scn = new Scanner(System.in); scn new Scanner(System.in) int a = scn.nextInt(); a scn.nextInt() scn.nextInt scn int b = scn.nextInt(); b scn.nextInt() scn.nextInt scn int c = scn.nextInt(); c scn.nextInt() scn.nextInt scn int d = scn.nextInt(); d scn.nextInt() scn.nextInt scn int x = c/b; x c/b c b int y = a/d; y a/d a d int xx = c%b; xx c%b c b int yy = a%d; yy a%d a d if(xx != 0){
        x = x+1;
      } xx != 0 xx 0 {
        x = x+1;
      } x = x+1 x x+1 x 1 if(yy != 0){
        y = y+1;
      } yy != 0 yy 0 {
        y = y+1;
      } y = y+1 y y+1 y 1 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 {
	public static void main(String[] args){
	Scanner scn = new Scanner(System.in);
	int a = scn.nextInt();
      int b = scn.nextInt();
      int c = scn.nextInt();
      int d = scn.nextInt();
      int x = c/b;
      int y = a/d;
      int xx = c%b;
      int yy = a%d;
      if(xx != 0){
        x = x+1;
      }
      if(yy != 0){
        y = y+1;
      }
      if(x<=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
	}
} public class Main {
	public static void main(String[] args){
	Scanner scn = new Scanner(System.in);
	int a = scn.nextInt();
      int b = scn.nextInt();
      int c = scn.nextInt();
      int d = scn.nextInt();
      int x = c/b;
      int y = a/d;
      int xx = c%b;
      int yy = a%d;
      if(xx != 0){
        x = x+1;
      }
      if(yy != 0){
        y = y+1;
      }
      if(x<=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
	}
} Main
import java.util.*;

public class Main {
	public static void main(String[] args){
	Scanner scn = new Scanner(System.in);
	int a = scn.nextInt();
      int b = scn.nextInt();
      int c = scn.nextInt();
      int d = scn.nextInt();
      int x = c/b;
      int y = a/d;
      int xx = c%b;
      int yy = a%d;
      if(xx != 0){
        x = x+1;
      }
      if(yy != 0){
        y = y+1;
      }
      if(x<=y){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
	}
}