import java.util.Scanner;


public class Main{
    
      public static int a,b,c,d;
      
      public static String solve(){
           int tak = 0,aok = 0;
           tak = ((c+b-1)/b);
           aok = ((a+d-1)/d);
           if( tak - aok <= 0 ) return "Yes";
           return "No";
      }
  	  public static void read(){
         Scanner x = new Scanner(System.in);
         a = x.nextInt();
         b = x.nextInt();
         c = x.nextInt();
         d = x.nextInt();   
      }

       public static void main(String []args){

         read();
         System.out.println(solve());
        
      }
} import java.util.Scanner; Scanner java.util public class Main{
    
      public static int a,b,c,d;
      
      public static String solve(){
           int tak = 0,aok = 0;
           tak = ((c+b-1)/b);
           aok = ((a+d-1)/d);
           if( tak - aok <= 0 ) return "Yes";
           return "No";
      }
  	  public static void read(){
         Scanner x = new Scanner(System.in);
         a = x.nextInt();
         b = x.nextInt();
         c = x.nextInt();
         d = x.nextInt();   
      }

       public static void main(String []args){

         read();
         System.out.println(solve());
        
      }
} Main public static int a a b b c c d; d public static String solve(){
           int tak = 0,aok = 0;
           tak = ((c+b-1)/b);
           aok = ((a+d-1)/d);
           if( tak - aok <= 0 ) return "Yes";
           return "No";
      } solve {
           int tak = 0,aok = 0;
           tak = ((c+b-1)/b);
           aok = ((a+d-1)/d);
           if( tak - aok <= 0 ) return "Yes";
           return "No";
      } int tak = 0 tak 0 aok = 0; aok 0 tak = ((c+b-1)/b) tak ((c+b-1)/b) (c+b-1) c+b c b 1 b aok = ((a+d-1)/d) aok ((a+d-1)/d) (a+d-1) a+d a d 1 d if( tak - aok <= 0 ) return "Yes"; tak - aok <= 0 tak - aok tak aok 0 return "Yes"; "Yes" return "No"; "No" public static void read(){
         Scanner x = new Scanner(System.in);
         a = x.nextInt();
         b = x.nextInt();
         c = x.nextInt();
         d = x.nextInt();   
      } read {
         Scanner x = new Scanner(System.in);
         a = x.nextInt();
         b = x.nextInt();
         c = x.nextInt();
         d = x.nextInt();   
      } Scanner x = new Scanner(System.in); x new Scanner(System.in) a = x.nextInt() a x.nextInt() x.nextInt x b = x.nextInt() b x.nextInt() x.nextInt x c = x.nextInt() c x.nextInt() x.nextInt x d = x.nextInt() d x.nextInt() x.nextInt x public static void main(String []args){

         read();
         System.out.println(solve());
        
      } main {

         read();
         System.out.println(solve());
        
      } read() read System.out.println(solve()) System.out.println System.out System System.out solve() solve String []args args public class Main{
    
      public static int a,b,c,d;
      
      public static String solve(){
           int tak = 0,aok = 0;
           tak = ((c+b-1)/b);
           aok = ((a+d-1)/d);
           if( tak - aok <= 0 ) return "Yes";
           return "No";
      }
  	  public static void read(){
         Scanner x = new Scanner(System.in);
         a = x.nextInt();
         b = x.nextInt();
         c = x.nextInt();
         d = x.nextInt();   
      }

       public static void main(String []args){

         read();
         System.out.println(solve());
        
      }
} public class Main{
    
      public static int a,b,c,d;
      
      public static String solve(){
           int tak = 0,aok = 0;
           tak = ((c+b-1)/b);
           aok = ((a+d-1)/d);
           if( tak - aok <= 0 ) return "Yes";
           return "No";
      }
  	  public static void read(){
         Scanner x = new Scanner(System.in);
         a = x.nextInt();
         b = x.nextInt();
         c = x.nextInt();
         d = x.nextInt();   
      }

       public static void main(String []args){

         read();
         System.out.println(solve());
        
      }
} Main
import java.util.Scanner;


public class Main{
    
      public static int a,b,c,d;
      
      public static String solve(){
           int tak = 0,aok = 0;
           tak = ((c+b-1)/b);
           aok = ((a+d-1)/d);
           if( tak - aok <= 0 ) return "Yes";
           return "No";
      }
  	  public static void read(){
         Scanner x = new Scanner(System.in);
         a = x.nextInt();
         b = x.nextInt();
         c = x.nextInt();
         d = x.nextInt();   
      }

       public static void main(String []args){

         read();
         System.out.println(solve());
        
      }
}