import java.util.*;
import java.io.*;
public class Main
{
    public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);
        // int T;
        // T=in.nextInt();
        // while((T--)>0)
        // {
        //     //code comes here

        // }   
            int TH,TS,HH,HS;
            TH=in.nextInt();
            TS=in.nextInt();
            HH=in.nextInt();
            HS=in.nextInt();
            int turnTaka=TH/HS;
            if(TH%HS!=0)
            ++turnTaka;
            int turnHaya=HH/TS;
            if(HH%TS!=0)
            ++turnHaya;
            if(turnHaya<=turnTaka)
            System.out.println("Yes");
            else
            System.out.println("No");

    }

} import java.util.*; util.* java import java.io.*; io.* java public class Main
{
    public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);
        // int T;
        // T=in.nextInt();
        // while((T--)>0)
        // {
        //     //code comes here

        // }   
            int TH,TS,HH,HS;
            TH=in.nextInt();
            TS=in.nextInt();
            HH=in.nextInt();
            HS=in.nextInt();
            int turnTaka=TH/HS;
            if(TH%HS!=0)
            ++turnTaka;
            int turnHaya=HH/TS;
            if(HH%TS!=0)
            ++turnHaya;
            if(turnHaya<=turnTaka)
            System.out.println("Yes");
            else
            System.out.println("No");

    }

} Main public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);
        // int T;
        // T=in.nextInt();
        // while((T--)>0)
        // {
        //     //code comes here

        // }   
            int TH,TS,HH,HS;
            TH=in.nextInt();
            TS=in.nextInt();
            HH=in.nextInt();
            HS=in.nextInt();
            int turnTaka=TH/HS;
            if(TH%HS!=0)
            ++turnTaka;
            int turnHaya=HH/TS;
            if(HH%TS!=0)
            ++turnHaya;
            if(turnHaya<=turnTaka)
            System.out.println("Yes");
            else
            System.out.println("No");

    } main {
        Scanner in = new Scanner(System.in);
        // int T;
        // T=in.nextInt();
        // while((T--)>0)
        // {
        //     //code comes here

        // }   
            int TH,TS,HH,HS;
            TH=in.nextInt();
            TS=in.nextInt();
            HH=in.nextInt();
            HS=in.nextInt();
            int turnTaka=TH/HS;
            if(TH%HS!=0)
            ++turnTaka;
            int turnHaya=HH/TS;
            if(HH%TS!=0)
            ++turnHaya;
            if(turnHaya<=turnTaka)
            System.out.println("Yes");
            else
            System.out.println("No");

    } Scanner in = new Scanner(System.in); in new Scanner(System.in) int TH TH TS TS HH HH HS; HS TH=in.nextInt() TH in.nextInt() in.nextInt in TS=in.nextInt() TS in.nextInt() in.nextInt in HH=in.nextInt() HH in.nextInt() in.nextInt in HS=in.nextInt() HS in.nextInt() in.nextInt in int turnTaka=TH/HS; turnTaka TH/HS TH HS if(TH%HS!=0)
            ++turnTaka; TH%HS!=0 TH%HS TH HS 0 ++turnTaka turnTaka int turnHaya=HH/TS; turnHaya HH/TS HH TS if(HH%TS!=0)
            ++turnHaya; HH%TS!=0 HH%TS HH TS 0 ++turnHaya turnHaya if(turnHaya<=turnTaka)
            System.out.println("Yes");
            else
            System.out.println("No"); turnHaya<=turnTaka turnHaya turnTaka 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 public class Main
{
    public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);
        // int T;
        // T=in.nextInt();
        // while((T--)>0)
        // {
        //     //code comes here

        // }   
            int TH,TS,HH,HS;
            TH=in.nextInt();
            TS=in.nextInt();
            HH=in.nextInt();
            HS=in.nextInt();
            int turnTaka=TH/HS;
            if(TH%HS!=0)
            ++turnTaka;
            int turnHaya=HH/TS;
            if(HH%TS!=0)
            ++turnHaya;
            if(turnHaya<=turnTaka)
            System.out.println("Yes");
            else
            System.out.println("No");

    }

} public class Main
{
    public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);
        // int T;
        // T=in.nextInt();
        // while((T--)>0)
        // {
        //     //code comes here

        // }   
            int TH,TS,HH,HS;
            TH=in.nextInt();
            TS=in.nextInt();
            HH=in.nextInt();
            HS=in.nextInt();
            int turnTaka=TH/HS;
            if(TH%HS!=0)
            ++turnTaka;
            int turnHaya=HH/TS;
            if(HH%TS!=0)
            ++turnHaya;
            if(turnHaya<=turnTaka)
            System.out.println("Yes");
            else
            System.out.println("No");

    }

} Main
import java.util.*;
import java.io.*;
public class Main
{
    public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);
        // int T;
        // T=in.nextInt();
        // while((T--)>0)
        // {
        //     //code comes here

        // }   
            int TH,TS,HH,HS;
            TH=in.nextInt();
            TS=in.nextInt();
            HH=in.nextInt();
            HS=in.nextInt();
            int turnTaka=TH/HS;
            if(TH%HS!=0)
            ++turnTaka;
            int turnHaya=HH/TS;
            if(HH%TS!=0)
            ++turnHaya;
            if(turnHaya<=turnTaka)
            System.out.println("Yes");
            else
            System.out.println("No");

    }

}