/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

import java.util.*;

/**
 *
 * @author Admin
 */
 class Main {
    
    
    public static void main(String args[])
    {
    Scanner s=new Scanner(System.in);
    
    int a=s.nextInt();
    
    int b=s.nextInt();
 
       int c=s.nextInt();
 
    int d=s.nextInt();
    
         
    while(a>0 && c>0)
    {
    
        c=c-b;
        if(c<=0)
            break;
        
       a=a-d;
      
    }
    
    if(a>0 && c<=0)
       System.out.println("Yes");
    else
           System.out.println("No");
    
    
    
    }
    
    
} import java.util.*; util.* java  class Main {
    
    
    public static void main(String args[])
    {
    Scanner s=new Scanner(System.in);
    
    int a=s.nextInt();
    
    int b=s.nextInt();
 
       int c=s.nextInt();
 
    int d=s.nextInt();
    
         
    while(a>0 && c>0)
    {
    
        c=c-b;
        if(c<=0)
            break;
        
       a=a-d;
      
    }
    
    if(a>0 && c<=0)
       System.out.println("Yes");
    else
           System.out.println("No");
    
    
    
    }
    
    
} Main public static void main(String args[])
    {
    Scanner s=new Scanner(System.in);
    
    int a=s.nextInt();
    
    int b=s.nextInt();
 
       int c=s.nextInt();
 
    int d=s.nextInt();
    
         
    while(a>0 && c>0)
    {
    
        c=c-b;
        if(c<=0)
            break;
        
       a=a-d;
      
    }
    
    if(a>0 && c<=0)
       System.out.println("Yes");
    else
           System.out.println("No");
    
    
    
    } main {
    Scanner s=new Scanner(System.in);
    
    int a=s.nextInt();
    
    int b=s.nextInt();
 
       int c=s.nextInt();
 
    int d=s.nextInt();
    
         
    while(a>0 && c>0)
    {
    
        c=c-b;
        if(c<=0)
            break;
        
       a=a-d;
      
    }
    
    if(a>0 && c<=0)
       System.out.println("Yes");
    else
           System.out.println("No");
    
    
    
    } Scanner s=new Scanner(System.in); s new Scanner(System.in) int a=s.nextInt(); a s.nextInt() s.nextInt s int b=s.nextInt(); b s.nextInt() s.nextInt s int c=s.nextInt(); c s.nextInt() s.nextInt s int d=s.nextInt(); d s.nextInt() s.nextInt s while(a>0 && c>0)
    {
    
        c=c-b;
        if(c<=0)
            break;
        
       a=a-d;
      
    } a>0 && c>0 a>0 a 0 c>0 c 0 {
    
        c=c-b;
        if(c<=0)
            break;
        
       a=a-d;
      
    } c=c-b c c-b c b if(c<=0)
            break; c<=0 c 0 break; a=a-d a a-d a d if(a>0 && c<=0)
       System.out.println("Yes");
    else
           System.out.println("No"); a>0 && c<=0 a>0 a 0 c<=0 c 0 System.out.println("Yes") System.out.println System.out System System.out "Yes" System.out.println("No") System.out.println System.out System System.out "No" String args[] args
/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

import java.util.*;

/**
 *
 * @author Admin
 */
 class Main {
    
    
    public static void main(String args[])
    {
    Scanner s=new Scanner(System.in);
    
    int a=s.nextInt();
    
    int b=s.nextInt();
 
       int c=s.nextInt();
 
    int d=s.nextInt();
    
         
    while(a>0 && c>0)
    {
    
        c=c-b;
        if(c<=0)
            break;
        
       a=a-d;
      
    }
    
    if(a>0 && c<=0)
       System.out.println("Yes");
    else
           System.out.println("No");
    
    
    
    }
    
    
}
