import java.util.Scanner;
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();
   boolean flag = true;

   while(flag) {
	   c -= b;
	   if(c<=0) {
		   System.out.println("Yes");
		   flag = false;
		   break;
	   }
	   a -= d;
	   if(a<=0) {
		   System.out.println("No");
		   flag = false;
		   break;
	   }
   }

 }
} import java.util.Scanner; Scanner java.util 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();
   boolean flag = true;

   while(flag) {
	   c -= b;
	   if(c<=0) {
		   System.out.println("Yes");
		   flag = false;
		   break;
	   }
	   a -= d;
	   if(a<=0) {
		   System.out.println("No");
		   flag = false;
		   break;
	   }
   }

 }
} 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();
   boolean flag = true;

   while(flag) {
	   c -= b;
	   if(c<=0) {
		   System.out.println("Yes");
		   flag = false;
		   break;
	   }
	   a -= d;
	   if(a<=0) {
		   System.out.println("No");
		   flag = false;
		   break;
	   }
   }

 } main {
   Scanner sc = new Scanner(System.in);
   int a= sc.nextInt();
   int b= sc.nextInt();
   int c= sc.nextInt();
   int d= sc.nextInt();
   boolean flag = true;

   while(flag) {
	   c -= b;
	   if(c<=0) {
		   System.out.println("Yes");
		   flag = false;
		   break;
	   }
	   a -= d;
	   if(a<=0) {
		   System.out.println("No");
		   flag = false;
		   break;
	   }
   }

 } 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 boolean flag = true; flag true while(flag) {
	   c -= b;
	   if(c<=0) {
		   System.out.println("Yes");
		   flag = false;
		   break;
	   }
	   a -= d;
	   if(a<=0) {
		   System.out.println("No");
		   flag = false;
		   break;
	   }
   } flag {
	   c -= b;
	   if(c<=0) {
		   System.out.println("Yes");
		   flag = false;
		   break;
	   }
	   a -= d;
	   if(a<=0) {
		   System.out.println("No");
		   flag = false;
		   break;
	   }
   } c -= b c b if(c<=0) {
		   System.out.println("Yes");
		   flag = false;
		   break;
	   } c<=0 c 0 {
		   System.out.println("Yes");
		   flag = false;
		   break;
	   } System.out.println("Yes") System.out.println System.out System System.out "Yes" flag = false flag false break; a -= d a d if(a<=0) {
		   System.out.println("No");
		   flag = false;
		   break;
	   } a<=0 a 0 {
		   System.out.println("No");
		   flag = false;
		   break;
	   } System.out.println("No") System.out.println System.out System System.out "No" flag = false flag false break; String args[] args
import java.util.Scanner;
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();
   boolean flag = true;

   while(flag) {
	   c -= b;
	   if(c<=0) {
		   System.out.println("Yes");
		   flag = false;
		   break;
	   }
	   a -= d;
	   if(a<=0) {
		   System.out.println("No");
		   flag = false;
		   break;
	   }
   }

 }
}