import java.util.*;


		       public class Main {

		           public static void main(String args[])  {
		        	   Scanner sc =new Scanner(System.in);
		        	   int lifeA = sc.nextInt();
		        	   int attackA = sc.nextInt();
		        	   int lifeB = sc.nextInt();
		        	   int attackB = sc.nextInt();	
                      while(lifeA>0 && lifeB>0) {
                    	  if(lifeA>0) {
                    		  lifeB -= attackA;
                    	  }
                    	  if(lifeB>0){
                    		  lifeA -=attackB;
                    	  }

                      }
                      if(lifeA <lifeB) {
                    	  System.out.println("No");
                      }else {
                    	  System.out.println("Yes");
                      }

		           }
		       }

 import java.util.*; util.* java public class Main {

		           public static void main(String args[])  {
		        	   Scanner sc =new Scanner(System.in);
		        	   int lifeA = sc.nextInt();
		        	   int attackA = sc.nextInt();
		        	   int lifeB = sc.nextInt();
		        	   int attackB = sc.nextInt();	
                      while(lifeA>0 && lifeB>0) {
                    	  if(lifeA>0) {
                    		  lifeB -= attackA;
                    	  }
                    	  if(lifeB>0){
                    		  lifeA -=attackB;
                    	  }

                      }
                      if(lifeA <lifeB) {
                    	  System.out.println("No");
                      }else {
                    	  System.out.println("Yes");
                      }

		           }
		       } Main public static void main(String args[])  {
		        	   Scanner sc =new Scanner(System.in);
		        	   int lifeA = sc.nextInt();
		        	   int attackA = sc.nextInt();
		        	   int lifeB = sc.nextInt();
		        	   int attackB = sc.nextInt();	
                      while(lifeA>0 && lifeB>0) {
                    	  if(lifeA>0) {
                    		  lifeB -= attackA;
                    	  }
                    	  if(lifeB>0){
                    		  lifeA -=attackB;
                    	  }

                      }
                      if(lifeA <lifeB) {
                    	  System.out.println("No");
                      }else {
                    	  System.out.println("Yes");
                      }

		           } main {
		        	   Scanner sc =new Scanner(System.in);
		        	   int lifeA = sc.nextInt();
		        	   int attackA = sc.nextInt();
		        	   int lifeB = sc.nextInt();
		        	   int attackB = sc.nextInt();	
                      while(lifeA>0 && lifeB>0) {
                    	  if(lifeA>0) {
                    		  lifeB -= attackA;
                    	  }
                    	  if(lifeB>0){
                    		  lifeA -=attackB;
                    	  }

                      }
                      if(lifeA <lifeB) {
                    	  System.out.println("No");
                      }else {
                    	  System.out.println("Yes");
                      }

		           } Scanner sc =new Scanner(System.in); sc new Scanner(System.in) int lifeA = sc.nextInt(); lifeA sc.nextInt() sc.nextInt sc int attackA = sc.nextInt(); attackA sc.nextInt() sc.nextInt sc int lifeB = sc.nextInt(); lifeB sc.nextInt() sc.nextInt sc int attackB = sc.nextInt(); attackB sc.nextInt() sc.nextInt sc while(lifeA>0 && lifeB>0) {
                    	  if(lifeA>0) {
                    		  lifeB -= attackA;
                    	  }
                    	  if(lifeB>0){
                    		  lifeA -=attackB;
                    	  }

                      } lifeA>0 && lifeB>0 lifeA>0 lifeA 0 lifeB>0 lifeB 0 {
                    	  if(lifeA>0) {
                    		  lifeB -= attackA;
                    	  }
                    	  if(lifeB>0){
                    		  lifeA -=attackB;
                    	  }

                      } if(lifeA>0) {
                    		  lifeB -= attackA;
                    	  } lifeA>0 lifeA 0 {
                    		  lifeB -= attackA;
                    	  } lifeB -= attackA lifeB attackA if(lifeB>0){
                    		  lifeA -=attackB;
                    	  } lifeB>0 lifeB 0 {
                    		  lifeA -=attackB;
                    	  } lifeA -=attackB lifeA attackB if(lifeA <lifeB) {
                    	  System.out.println("No");
                      }else {
                    	  System.out.println("Yes");
                      } lifeA <lifeB lifeA lifeB {
                    	  System.out.println("No");
                      } System.out.println("No") System.out.println System.out System System.out "No" {
                    	  System.out.println("Yes");
                      } System.out.println("Yes") System.out.println System.out System System.out "Yes" String args[] args public class Main {

		           public static void main(String args[])  {
		        	   Scanner sc =new Scanner(System.in);
		        	   int lifeA = sc.nextInt();
		        	   int attackA = sc.nextInt();
		        	   int lifeB = sc.nextInt();
		        	   int attackB = sc.nextInt();	
                      while(lifeA>0 && lifeB>0) {
                    	  if(lifeA>0) {
                    		  lifeB -= attackA;
                    	  }
                    	  if(lifeB>0){
                    		  lifeA -=attackB;
                    	  }

                      }
                      if(lifeA <lifeB) {
                    	  System.out.println("No");
                      }else {
                    	  System.out.println("Yes");
                      }

		           }
		       } public class Main {

		           public static void main(String args[])  {
		        	   Scanner sc =new Scanner(System.in);
		        	   int lifeA = sc.nextInt();
		        	   int attackA = sc.nextInt();
		        	   int lifeB = sc.nextInt();
		        	   int attackB = sc.nextInt();	
                      while(lifeA>0 && lifeB>0) {
                    	  if(lifeA>0) {
                    		  lifeB -= attackA;
                    	  }
                    	  if(lifeB>0){
                    		  lifeA -=attackB;
                    	  }

                      }
                      if(lifeA <lifeB) {
                    	  System.out.println("No");
                      }else {
                    	  System.out.println("Yes");
                      }

		           }
		       } Main
import java.util.*;


		       public class Main {

		           public static void main(String args[])  {
		        	   Scanner sc =new Scanner(System.in);
		        	   int lifeA = sc.nextInt();
		        	   int attackA = sc.nextInt();
		        	   int lifeB = sc.nextInt();
		        	   int attackB = sc.nextInt();	
                      while(lifeA>0 && lifeB>0) {
                    	  if(lifeA>0) {
                    		  lifeB -= attackA;
                    	  }
                    	  if(lifeB>0){
                    		  lifeA -=attackB;
                    	  }

                      }
                      if(lifeA <lifeB) {
                    	  System.out.println("No");
                      }else {
                    	  System.out.println("Yes");
                      }

		           }
		       }


