import java.io.*;
import java.util.*;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(in.readLine());
		
		int A = Integer.parseInt(st.nextToken());
		int B = Integer.parseInt(st.nextToken());
		int C = Integer.parseInt(st.nextToken());
		int D = Integer.parseInt(st.nextToken());
		
		int t1 = (int) Math.ceil((double) C / B);
		int t2 = (int) Math.ceil((double) A / D);
		
		if (t1 <= t2)
			System.out.println("Yes");
		else
			System.out.println("No");
	}
} import java.io.*; io.* java import java.util.*; util.* java public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(in.readLine());
		
		int A = Integer.parseInt(st.nextToken());
		int B = Integer.parseInt(st.nextToken());
		int C = Integer.parseInt(st.nextToken());
		int D = Integer.parseInt(st.nextToken());
		
		int t1 = (int) Math.ceil((double) C / B);
		int t2 = (int) Math.ceil((double) A / D);
		
		if (t1 <= t2)
			System.out.println("Yes");
		else
			System.out.println("No");
	}
} Main public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(in.readLine());
		
		int A = Integer.parseInt(st.nextToken());
		int B = Integer.parseInt(st.nextToken());
		int C = Integer.parseInt(st.nextToken());
		int D = Integer.parseInt(st.nextToken());
		
		int t1 = (int) Math.ceil((double) C / B);
		int t2 = (int) Math.ceil((double) A / D);
		
		if (t1 <= t2)
			System.out.println("Yes");
		else
			System.out.println("No");
	} main {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(in.readLine());
		
		int A = Integer.parseInt(st.nextToken());
		int B = Integer.parseInt(st.nextToken());
		int C = Integer.parseInt(st.nextToken());
		int D = Integer.parseInt(st.nextToken());
		
		int t1 = (int) Math.ceil((double) C / B);
		int t2 = (int) Math.ceil((double) A / D);
		
		if (t1 <= t2)
			System.out.println("Yes");
		else
			System.out.println("No");
	} BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); in new BufferedReader(new InputStreamReader(System.in)) StringTokenizer st = new StringTokenizer(in.readLine()); st new StringTokenizer(in.readLine()) int A = Integer.parseInt(st.nextToken()); A Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st int B = Integer.parseInt(st.nextToken()); B Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st int C = Integer.parseInt(st.nextToken()); C Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st int D = Integer.parseInt(st.nextToken()); D Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st int t1 = (int) Math.ceil((double) C / B); t1 (int) Math.ceil((double) C / B) Math.ceil Math (double) C / B (double) C B int t2 = (int) Math.ceil((double) A / D); t2 (int) Math.ceil((double) A / D) Math.ceil Math (double) A / D (double) A D if (t1 <= t2)
			System.out.println("Yes");
		else
			System.out.println("No"); t1 <= t2 t1 t2 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 in = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(in.readLine());
		
		int A = Integer.parseInt(st.nextToken());
		int B = Integer.parseInt(st.nextToken());
		int C = Integer.parseInt(st.nextToken());
		int D = Integer.parseInt(st.nextToken());
		
		int t1 = (int) Math.ceil((double) C / B);
		int t2 = (int) Math.ceil((double) A / D);
		
		if (t1 <= t2)
			System.out.println("Yes");
		else
			System.out.println("No");
	}
} public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(in.readLine());
		
		int A = Integer.parseInt(st.nextToken());
		int B = Integer.parseInt(st.nextToken());
		int C = Integer.parseInt(st.nextToken());
		int D = Integer.parseInt(st.nextToken());
		
		int t1 = (int) Math.ceil((double) C / B);
		int t2 = (int) Math.ceil((double) A / D);
		
		if (t1 <= t2)
			System.out.println("Yes");
		else
			System.out.println("No");
	}
} Main
import java.io.*;
import java.util.*;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(in.readLine());
		
		int A = Integer.parseInt(st.nextToken());
		int B = Integer.parseInt(st.nextToken());
		int C = Integer.parseInt(st.nextToken());
		int D = Integer.parseInt(st.nextToken());
		
		int t1 = (int) Math.ceil((double) C / B);
		int t2 = (int) Math.ceil((double) A / D);
		
		if (t1 <= t2)
			System.out.println("Yes");
		else
			System.out.println("No");
	}
}