import java.io.*;
import java.lang.*;
import java.util.*;
public class Main{  
    public static void main(String[] args) throws IOException{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String[] str=br.readLine().split(" ");
        long A=Long.parseLong(str[0]);
        long B=Long.parseLong(str[1]);
        long C=Long.parseLong(str[2]);
        long D=Long.parseLong(str[3]);
        long E=(A%D==0)?A/D:A/D+1;
        long F=(C%B==0)?C/B:C/B+1;
        if(F<=E) System.out.println("Yes");
        else System.out.println("No");
        }
    } import java.io.*; io.* java import java.lang.*; lang.* java import java.util.*; util.* java public class Main{  
    public static void main(String[] args) throws IOException{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String[] str=br.readLine().split(" ");
        long A=Long.parseLong(str[0]);
        long B=Long.parseLong(str[1]);
        long C=Long.parseLong(str[2]);
        long D=Long.parseLong(str[3]);
        long E=(A%D==0)?A/D:A/D+1;
        long F=(C%B==0)?C/B:C/B+1;
        if(F<=E) System.out.println("Yes");
        else System.out.println("No");
        }
    } Main public static void main(String[] args) throws IOException{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String[] str=br.readLine().split(" ");
        long A=Long.parseLong(str[0]);
        long B=Long.parseLong(str[1]);
        long C=Long.parseLong(str[2]);
        long D=Long.parseLong(str[3]);
        long E=(A%D==0)?A/D:A/D+1;
        long F=(C%B==0)?C/B:C/B+1;
        if(F<=E) System.out.println("Yes");
        else System.out.println("No");
        } main {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String[] str=br.readLine().split(" ");
        long A=Long.parseLong(str[0]);
        long B=Long.parseLong(str[1]);
        long C=Long.parseLong(str[2]);
        long D=Long.parseLong(str[3]);
        long E=(A%D==0)?A/D:A/D+1;
        long F=(C%B==0)?C/B:C/B+1;
        if(F<=E) System.out.println("Yes");
        else System.out.println("No");
        } BufferedReader br=new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) String[] str=br.readLine().split(" "); str br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " long A=Long.parseLong(str[0]); A Long.parseLong(str[0]) Long.parseLong Long str[0] str 0 long B=Long.parseLong(str[1]); B Long.parseLong(str[1]) Long.parseLong Long str[1] str 1 long C=Long.parseLong(str[2]); C Long.parseLong(str[2]) Long.parseLong Long str[2] str 2 long D=Long.parseLong(str[3]); D Long.parseLong(str[3]) Long.parseLong Long str[3] str 3 long E=(A%D==0)?A/D:A/D+1; E (A%D==0)?A/D:A/D+1 (A%D==0) A%D A D 0 A/D A D A/D+1 A/D A D 1 long F=(C%B==0)?C/B:C/B+1; F (C%B==0)?C/B:C/B+1 (C%B==0) C%B C B 0 C/B C B C/B+1 C/B C B 1 if(F<=E) System.out.println("Yes");
        else System.out.println("No"); F<=E F E 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) throws IOException{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String[] str=br.readLine().split(" ");
        long A=Long.parseLong(str[0]);
        long B=Long.parseLong(str[1]);
        long C=Long.parseLong(str[2]);
        long D=Long.parseLong(str[3]);
        long E=(A%D==0)?A/D:A/D+1;
        long F=(C%B==0)?C/B:C/B+1;
        if(F<=E) System.out.println("Yes");
        else System.out.println("No");
        }
    } public class Main{  
    public static void main(String[] args) throws IOException{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String[] str=br.readLine().split(" ");
        long A=Long.parseLong(str[0]);
        long B=Long.parseLong(str[1]);
        long C=Long.parseLong(str[2]);
        long D=Long.parseLong(str[3]);
        long E=(A%D==0)?A/D:A/D+1;
        long F=(C%B==0)?C/B:C/B+1;
        if(F<=E) System.out.println("Yes");
        else System.out.println("No");
        }
    } Main
import java.io.*;
import java.lang.*;
import java.util.*;
public class Main{  
    public static void main(String[] args) throws IOException{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String[] str=br.readLine().split(" ");
        long A=Long.parseLong(str[0]);
        long B=Long.parseLong(str[1]);
        long C=Long.parseLong(str[2]);
        long D=Long.parseLong(str[3]);
        long E=(A%D==0)?A/D:A/D+1;
        long F=(C%B==0)?C/B:C/B+1;
        if(F<=E) System.out.println("Yes");
        else System.out.println("No");
        }
    }
