import java.util.*;
import java.io.*;

class Main {
	public static void main (String[] args) {
		Scanner input=new Scanner(System.in);
		int a,b,c,d;
		a=input.nextInt();
		b=input.nextInt();
		c=input.nextInt();
		d=input.nextInt();
		do{
		    c=c-b;
		  //   System.out.println("c" + c);
		    if(c<=0)
		        break;
		    a=a-d;
		  //  System.out.println("a" + a);
		    if(a<=0)
		        break;
		}while(c>0 && a>0);
		if(c<=0)
		     System.out.println("Yes");
		 else
		    System.out.println("No");
		input.close();
	}
} import java.util.*; util.* java import java.io.*; io.* java class Main {
	public static void main (String[] args) {
		Scanner input=new Scanner(System.in);
		int a,b,c,d;
		a=input.nextInt();
		b=input.nextInt();
		c=input.nextInt();
		d=input.nextInt();
		do{
		    c=c-b;
		  //   System.out.println("c" + c);
		    if(c<=0)
		        break;
		    a=a-d;
		  //  System.out.println("a" + a);
		    if(a<=0)
		        break;
		}while(c>0 && a>0);
		if(c<=0)
		     System.out.println("Yes");
		 else
		    System.out.println("No");
		input.close();
	}
} Main public static void main (String[] args) {
		Scanner input=new Scanner(System.in);
		int a,b,c,d;
		a=input.nextInt();
		b=input.nextInt();
		c=input.nextInt();
		d=input.nextInt();
		do{
		    c=c-b;
		  //   System.out.println("c" + c);
		    if(c<=0)
		        break;
		    a=a-d;
		  //  System.out.println("a" + a);
		    if(a<=0)
		        break;
		}while(c>0 && a>0);
		if(c<=0)
		     System.out.println("Yes");
		 else
		    System.out.println("No");
		input.close();
	} main {
		Scanner input=new Scanner(System.in);
		int a,b,c,d;
		a=input.nextInt();
		b=input.nextInt();
		c=input.nextInt();
		d=input.nextInt();
		do{
		    c=c-b;
		  //   System.out.println("c" + c);
		    if(c<=0)
		        break;
		    a=a-d;
		  //  System.out.println("a" + a);
		    if(a<=0)
		        break;
		}while(c>0 && a>0);
		if(c<=0)
		     System.out.println("Yes");
		 else
		    System.out.println("No");
		input.close();
	} Scanner input=new Scanner(System.in); input new Scanner(System.in) int a a b b c c d; d a=input.nextInt() a input.nextInt() input.nextInt input b=input.nextInt() b input.nextInt() input.nextInt input c=input.nextInt() c input.nextInt() input.nextInt input d=input.nextInt() d input.nextInt() input.nextInt input do{
		    c=c-b;
		  //   System.out.println("c" + c);
		    if(c<=0)
		        break;
		    a=a-d;
		  //  System.out.println("a" + a);
		    if(a<=0)
		        break;
		}while(c>0 && a>0); c>0 && a>0 c>0 c 0 a>0 a 0 {
		    c=c-b;
		  //   System.out.println("c" + c);
		    if(c<=0)
		        break;
		    a=a-d;
		  //  System.out.println("a" + a);
		    if(a<=0)
		        break;
		} 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)
		        break; a<=0 a 0 break; if(c<=0)
		     System.out.println("Yes");
		 else
		    System.out.println("No"); 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" input.close() input.close input String[] args args
import java.util.*;
import java.io.*;

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