import java.util.Scanner;
 
public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int A=sc.nextInt();
    int B=sc.nextInt();
    int C=sc.nextInt();
    int D=sc.nextInt();
    
    int X=(A-1)/D;
    int Y=(C-1)/B;
    
    if(Y>X) {
    	System.out.println("No");
    }else {
    	System.out.println("Yes");
    }
  }
    } import java.util.Scanner; Scanner java.util public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int A=sc.nextInt();
    int B=sc.nextInt();
    int C=sc.nextInt();
    int D=sc.nextInt();
    
    int X=(A-1)/D;
    int Y=(C-1)/B;
    
    if(Y>X) {
    	System.out.println("No");
    }else {
    	System.out.println("Yes");
    }
  }
    } Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int A=sc.nextInt();
    int B=sc.nextInt();
    int C=sc.nextInt();
    int D=sc.nextInt();
    
    int X=(A-1)/D;
    int Y=(C-1)/B;
    
    if(Y>X) {
    	System.out.println("No");
    }else {
    	System.out.println("Yes");
    }
  } main {
    Scanner sc = new Scanner(System.in);
    int A=sc.nextInt();
    int B=sc.nextInt();
    int C=sc.nextInt();
    int D=sc.nextInt();
    
    int X=(A-1)/D;
    int Y=(C-1)/B;
    
    if(Y>X) {
    	System.out.println("No");
    }else {
    	System.out.println("Yes");
    }
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int A=sc.nextInt(); A sc.nextInt() sc.nextInt sc int B=sc.nextInt(); B sc.nextInt() sc.nextInt sc int C=sc.nextInt(); C sc.nextInt() sc.nextInt sc int D=sc.nextInt(); D sc.nextInt() sc.nextInt sc int X=(A-1)/D; X (A-1)/D (A-1) A 1 D int Y=(C-1)/B; Y (C-1)/B (C-1) C 1 B if(Y>X) {
    	System.out.println("No");
    }else {
    	System.out.println("Yes");
    } Y>X Y X {
    	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 A=sc.nextInt();
    int B=sc.nextInt();
    int C=sc.nextInt();
    int D=sc.nextInt();
    
    int X=(A-1)/D;
    int Y=(C-1)/B;
    
    if(Y>X) {
    	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 A=sc.nextInt();
    int B=sc.nextInt();
    int C=sc.nextInt();
    int D=sc.nextInt();
    
    int X=(A-1)/D;
    int Y=(C-1)/B;
    
    if(Y>X) {
    	System.out.println("No");
    }else {
    	System.out.println("Yes");
    }
  }
    } Main
import java.util.Scanner;
 
public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int A=sc.nextInt();
    int B=sc.nextInt();
    int C=sc.nextInt();
    int D=sc.nextInt();
    
    int X=(A-1)/D;
    int Y=(C-1)/B;
    
    if(Y>X) {
    	System.out.println("No");
    }else {
    	System.out.println("Yes");
    }
  }
    }