import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

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

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		double th = Integer.parseInt(st.nextToken());
		double ts = Integer.parseInt(st.nextToken());
		double ah = Integer.parseInt(st.nextToken());
		double as = Integer.parseInt(st.nextToken());
		System.out.println(Math.ceil(th / as) >= Math.ceil(ah / ts) ? "Yes" : "No");
	}
}
