import java.util.*;
import java.io.*;
class Main {
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st= new StringTokenizer(br.readLine());
        int th = Integer.parseInt(st.nextToken());
        int ts = Integer.parseInt(st.nextToken());
        int ah = Integer.parseInt(st.nextToken());
        int as = Integer.parseInt(st.nextToken());

        int tnum = ah%ts==0?ah/ts:(ah/ts) +1;
        int anum = th%as==0?th/as:(th/as) +1;
        String ans = tnum>anum? "No":"Yes";
        System.out.println(ans);
        

    }
} import java.util.*; util.* java import java.io.*; io.* java class Main {
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st= new StringTokenizer(br.readLine());
        int th = Integer.parseInt(st.nextToken());
        int ts = Integer.parseInt(st.nextToken());
        int ah = Integer.parseInt(st.nextToken());
        int as = Integer.parseInt(st.nextToken());

        int tnum = ah%ts==0?ah/ts:(ah/ts) +1;
        int anum = th%as==0?th/as:(th/as) +1;
        String ans = tnum>anum? "No":"Yes";
        System.out.println(ans);
        

    }
} Main public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st= new StringTokenizer(br.readLine());
        int th = Integer.parseInt(st.nextToken());
        int ts = Integer.parseInt(st.nextToken());
        int ah = Integer.parseInt(st.nextToken());
        int as = Integer.parseInt(st.nextToken());

        int tnum = ah%ts==0?ah/ts:(ah/ts) +1;
        int anum = th%as==0?th/as:(th/as) +1;
        String ans = tnum>anum? "No":"Yes";
        System.out.println(ans);
        

    } main {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st= new StringTokenizer(br.readLine());
        int th = Integer.parseInt(st.nextToken());
        int ts = Integer.parseInt(st.nextToken());
        int ah = Integer.parseInt(st.nextToken());
        int as = Integer.parseInt(st.nextToken());

        int tnum = ah%ts==0?ah/ts:(ah/ts) +1;
        int anum = th%as==0?th/as:(th/as) +1;
        String ans = tnum>anum? "No":"Yes";
        System.out.println(ans);
        

    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) StringTokenizer st= new StringTokenizer(br.readLine()); st new StringTokenizer(br.readLine()) int th = Integer.parseInt(st.nextToken()); th Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st int ts = Integer.parseInt(st.nextToken()); ts Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st int ah = Integer.parseInt(st.nextToken()); ah Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st int as = Integer.parseInt(st.nextToken()); as Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st int tnum = ah%ts==0?ah/ts:(ah/ts) +1; tnum ah%ts==0?ah/ts:(ah/ts) +1 ah%ts==0 ah%ts ah ts 0 ah/ts ah ts (ah/ts) +1 (ah/ts) ah ts 1 int anum = th%as==0?th/as:(th/as) +1; anum th%as==0?th/as:(th/as) +1 th%as==0 th%as th as 0 th/as th as (th/as) +1 (th/as) th as 1 String ans = tnum>anum? "No":"Yes"; ans tnum>anum? "No":"Yes" tnum>anum tnum anum "No" "Yes" System.out.println(ans) System.out.println System.out System System.out ans String[] args args
import java.util.*;
import java.io.*;
class Main {
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st= new StringTokenizer(br.readLine());
        int th = Integer.parseInt(st.nextToken());
        int ts = Integer.parseInt(st.nextToken());
        int ah = Integer.parseInt(st.nextToken());
        int as = Integer.parseInt(st.nextToken());

        int tnum = ah%ts==0?ah/ts:(ah/ts) +1;
        int anum = th%as==0?th/as:(th/as) +1;
        String ans = tnum>anum? "No":"Yes";
        System.out.println(ans);
        

    }
}