import java.util.*;
import java.io.*;
public class Main
{
    public static void main(String args[])throws Exception
    {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw=new PrintWriter(System.out);
        String str[]=br.readLine().split(" ");
        int a=Integer.parseInt(str[0]);
        int b=Integer.parseInt(str[1]);
        int c=Integer.parseInt(str[2]);
        int d=Integer.parseInt(str[3]);
        int tak=(int)Math.ceil((double)c/b);
        int aok=(int)Math.ceil((double)a/d);
        if(tak<=aok)
        pw.println("Yes");
        else
        pw.println("No");
        pw.flush();
        pw.close();
    }
} import java.util.*; util.* java import java.io.*; io.* java public class Main
{
    public static void main(String args[])throws Exception
    {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw=new PrintWriter(System.out);
        String str[]=br.readLine().split(" ");
        int a=Integer.parseInt(str[0]);
        int b=Integer.parseInt(str[1]);
        int c=Integer.parseInt(str[2]);
        int d=Integer.parseInt(str[3]);
        int tak=(int)Math.ceil((double)c/b);
        int aok=(int)Math.ceil((double)a/d);
        if(tak<=aok)
        pw.println("Yes");
        else
        pw.println("No");
        pw.flush();
        pw.close();
    }
} Main public static void main(String args[])throws Exception
    {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw=new PrintWriter(System.out);
        String str[]=br.readLine().split(" ");
        int a=Integer.parseInt(str[0]);
        int b=Integer.parseInt(str[1]);
        int c=Integer.parseInt(str[2]);
        int d=Integer.parseInt(str[3]);
        int tak=(int)Math.ceil((double)c/b);
        int aok=(int)Math.ceil((double)a/d);
        if(tak<=aok)
        pw.println("Yes");
        else
        pw.println("No");
        pw.flush();
        pw.close();
    } main {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw=new PrintWriter(System.out);
        String str[]=br.readLine().split(" ");
        int a=Integer.parseInt(str[0]);
        int b=Integer.parseInt(str[1]);
        int c=Integer.parseInt(str[2]);
        int d=Integer.parseInt(str[3]);
        int tak=(int)Math.ceil((double)c/b);
        int aok=(int)Math.ceil((double)a/d);
        if(tak<=aok)
        pw.println("Yes");
        else
        pw.println("No");
        pw.flush();
        pw.close();
    } BufferedReader br=new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) PrintWriter pw=new PrintWriter(System.out); pw new PrintWriter(System.out) String str[]=br.readLine().split(" "); str br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " int a=Integer.parseInt(str[0]); a Integer.parseInt(str[0]) Integer.parseInt Integer str[0] str 0 int b=Integer.parseInt(str[1]); b Integer.parseInt(str[1]) Integer.parseInt Integer str[1] str 1 int c=Integer.parseInt(str[2]); c Integer.parseInt(str[2]) Integer.parseInt Integer str[2] str 2 int d=Integer.parseInt(str[3]); d Integer.parseInt(str[3]) Integer.parseInt Integer str[3] str 3 int tak=(int)Math.ceil((double)c/b); tak (int)Math.ceil((double)c/b) Math.ceil Math (double)c/b (double)c b int aok=(int)Math.ceil((double)a/d); aok (int)Math.ceil((double)a/d) Math.ceil Math (double)a/d (double)a d if(tak<=aok)
        pw.println("Yes");
        else
        pw.println("No"); tak<=aok tak aok pw.println("Yes") pw.println pw "Yes" pw.println("No") pw.println pw "No" pw.flush() pw.flush pw pw.close() pw.close pw String args[] args public class Main
{
    public static void main(String args[])throws Exception
    {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw=new PrintWriter(System.out);
        String str[]=br.readLine().split(" ");
        int a=Integer.parseInt(str[0]);
        int b=Integer.parseInt(str[1]);
        int c=Integer.parseInt(str[2]);
        int d=Integer.parseInt(str[3]);
        int tak=(int)Math.ceil((double)c/b);
        int aok=(int)Math.ceil((double)a/d);
        if(tak<=aok)
        pw.println("Yes");
        else
        pw.println("No");
        pw.flush();
        pw.close();
    }
} public class Main
{
    public static void main(String args[])throws Exception
    {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw=new PrintWriter(System.out);
        String str[]=br.readLine().split(" ");
        int a=Integer.parseInt(str[0]);
        int b=Integer.parseInt(str[1]);
        int c=Integer.parseInt(str[2]);
        int d=Integer.parseInt(str[3]);
        int tak=(int)Math.ceil((double)c/b);
        int aok=(int)Math.ceil((double)a/d);
        if(tak<=aok)
        pw.println("Yes");
        else
        pw.println("No");
        pw.flush();
        pw.close();
    }
} Main
import java.util.*;
import java.io.*;
public class Main
{
    public static void main(String args[])throws Exception
    {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw=new PrintWriter(System.out);
        String str[]=br.readLine().split(" ");
        int a=Integer.parseInt(str[0]);
        int b=Integer.parseInt(str[1]);
        int c=Integer.parseInt(str[2]);
        int d=Integer.parseInt(str[3]);
        int tak=(int)Math.ceil((double)c/b);
        int aok=(int)Math.ceil((double)a/d);
        if(tak<=aok)
        pw.println("Yes");
        else
        pw.println("No");
        pw.flush();
        pw.close();
    }
}