import java.util.Scanner;

public class Main 
{
	public static void main(String[] args) 
	{
		Scanner sc = new Scanner(System.in);
		
		int th = sc.nextInt();
		int ts = sc.nextInt();
		
		int ah = sc.nextInt();
		int as = sc.nextInt();
		
		int tm = ah%ts;
		int t  = ah/ts;
		if(tm > 0)
		{
			t++;
		}
		
		int am = th%as;
		int a  = th/as;
		if(am > 0)
		{
			a++;
		}
		
		if(t <= a)
		{
			System.out.println("Yes");
		}
		else
		{
			System.out.println("No");
		}
		
	
		
		sc.close();
		
		

	}

} import java.util.Scanner; Scanner java.util public class Main 
{
	public static void main(String[] args) 
	{
		Scanner sc = new Scanner(System.in);
		
		int th = sc.nextInt();
		int ts = sc.nextInt();
		
		int ah = sc.nextInt();
		int as = sc.nextInt();
		
		int tm = ah%ts;
		int t  = ah/ts;
		if(tm > 0)
		{
			t++;
		}
		
		int am = th%as;
		int a  = th/as;
		if(am > 0)
		{
			a++;
		}
		
		if(t <= a)
		{
			System.out.println("Yes");
		}
		else
		{
			System.out.println("No");
		}
		
	
		
		sc.close();
		
		

	}

} Main public static void main(String[] args) 
	{
		Scanner sc = new Scanner(System.in);
		
		int th = sc.nextInt();
		int ts = sc.nextInt();
		
		int ah = sc.nextInt();
		int as = sc.nextInt();
		
		int tm = ah%ts;
		int t  = ah/ts;
		if(tm > 0)
		{
			t++;
		}
		
		int am = th%as;
		int a  = th/as;
		if(am > 0)
		{
			a++;
		}
		
		if(t <= a)
		{
			System.out.println("Yes");
		}
		else
		{
			System.out.println("No");
		}
		
	
		
		sc.close();
		
		

	} main {
		Scanner sc = new Scanner(System.in);
		
		int th = sc.nextInt();
		int ts = sc.nextInt();
		
		int ah = sc.nextInt();
		int as = sc.nextInt();
		
		int tm = ah%ts;
		int t  = ah/ts;
		if(tm > 0)
		{
			t++;
		}
		
		int am = th%as;
		int a  = th/as;
		if(am > 0)
		{
			a++;
		}
		
		if(t <= a)
		{
			System.out.println("Yes");
		}
		else
		{
			System.out.println("No");
		}
		
	
		
		sc.close();
		
		

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int th = sc.nextInt(); th sc.nextInt() sc.nextInt sc int ts = sc.nextInt(); ts sc.nextInt() sc.nextInt sc int ah = sc.nextInt(); ah sc.nextInt() sc.nextInt sc int as = sc.nextInt(); as sc.nextInt() sc.nextInt sc int tm = ah%ts; tm ah%ts ah ts int t  = ah/ts; t ah/ts ah ts if(tm > 0)
		{
			t++;
		} tm > 0 tm 0 {
			t++;
		} t++ t int am = th%as; am th%as th as int a  = th/as; a th/as th as if(am > 0)
		{
			a++;
		} am > 0 am 0 {
			a++;
		} a++ a if(t <= a)
		{
			System.out.println("Yes");
		}
		else
		{
			System.out.println("No");
		} t <= a t a {
			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" sc.close() sc.close sc String[] args args public class Main 
{
	public static void main(String[] args) 
	{
		Scanner sc = new Scanner(System.in);
		
		int th = sc.nextInt();
		int ts = sc.nextInt();
		
		int ah = sc.nextInt();
		int as = sc.nextInt();
		
		int tm = ah%ts;
		int t  = ah/ts;
		if(tm > 0)
		{
			t++;
		}
		
		int am = th%as;
		int a  = th/as;
		if(am > 0)
		{
			a++;
		}
		
		if(t <= a)
		{
			System.out.println("Yes");
		}
		else
		{
			System.out.println("No");
		}
		
	
		
		sc.close();
		
		

	}

} public class Main 
{
	public static void main(String[] args) 
	{
		Scanner sc = new Scanner(System.in);
		
		int th = sc.nextInt();
		int ts = sc.nextInt();
		
		int ah = sc.nextInt();
		int as = sc.nextInt();
		
		int tm = ah%ts;
		int t  = ah/ts;
		if(tm > 0)
		{
			t++;
		}
		
		int am = th%as;
		int a  = th/as;
		if(am > 0)
		{
			a++;
		}
		
		if(t <= a)
		{
			System.out.println("Yes");
		}
		else
		{
			System.out.println("No");
		}
		
	
		
		sc.close();
		
		

	}

} Main
import java.util.Scanner;

public class Main 
{
	public static void main(String[] args) 
	{
		Scanner sc = new Scanner(System.in);
		
		int th = sc.nextInt();
		int ts = sc.nextInt();
		
		int ah = sc.nextInt();
		int as = sc.nextInt();
		
		int tm = ah%ts;
		int t  = ah/ts;
		if(tm > 0)
		{
			t++;
		}
		
		int am = th%as;
		int a  = th/as;
		if(am > 0)
		{
			a++;
		}
		
		if(t <= a)
		{
			System.out.println("Yes");
		}
		else
		{
			System.out.println("No");
		}
		
	
		
		sc.close();
		
		

	}

}
