

import java.util.Scanner;

public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int thp = sc.nextInt();
		int ta = sc.nextInt();
		int ahp = sc.nextInt();
		int aa = sc.nextInt();

		while (thp > 0) {
			ahp -= ta;
			if (ahp <= 0)
				break;
			thp -= aa;
		}
		if (thp <= 0)
			System.out.println("No");
		else
			System.out.println("Yes");
	}

} import java.util.Scanner; Scanner java.util public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int thp = sc.nextInt();
		int ta = sc.nextInt();
		int ahp = sc.nextInt();
		int aa = sc.nextInt();

		while (thp > 0) {
			ahp -= ta;
			if (ahp <= 0)
				break;
			thp -= aa;
		}
		if (thp <= 0)
			System.out.println("No");
		else
			System.out.println("Yes");
	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int thp = sc.nextInt();
		int ta = sc.nextInt();
		int ahp = sc.nextInt();
		int aa = sc.nextInt();

		while (thp > 0) {
			ahp -= ta;
			if (ahp <= 0)
				break;
			thp -= aa;
		}
		if (thp <= 0)
			System.out.println("No");
		else
			System.out.println("Yes");
	} main {
		Scanner sc = new Scanner(System.in);

		int thp = sc.nextInt();
		int ta = sc.nextInt();
		int ahp = sc.nextInt();
		int aa = sc.nextInt();

		while (thp > 0) {
			ahp -= ta;
			if (ahp <= 0)
				break;
			thp -= aa;
		}
		if (thp <= 0)
			System.out.println("No");
		else
			System.out.println("Yes");
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int thp = sc.nextInt(); thp sc.nextInt() sc.nextInt sc int ta = sc.nextInt(); ta sc.nextInt() sc.nextInt sc int ahp = sc.nextInt(); ahp sc.nextInt() sc.nextInt sc int aa = sc.nextInt(); aa sc.nextInt() sc.nextInt sc while (thp > 0) {
			ahp -= ta;
			if (ahp <= 0)
				break;
			thp -= aa;
		} thp > 0 thp 0 {
			ahp -= ta;
			if (ahp <= 0)
				break;
			thp -= aa;
		} ahp -= ta ahp ta if (ahp <= 0)
				break; ahp <= 0 ahp 0 break; thp -= aa thp aa if (thp <= 0)
			System.out.println("No");
		else
			System.out.println("Yes"); thp <= 0 thp 0 System.out.println("No") System.out.println System.out System System.out "No" System.out.println("Yes") System.out.println System.out System System.out "Yes" String[] args args public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int thp = sc.nextInt();
		int ta = sc.nextInt();
		int ahp = sc.nextInt();
		int aa = sc.nextInt();

		while (thp > 0) {
			ahp -= ta;
			if (ahp <= 0)
				break;
			thp -= aa;
		}
		if (thp <= 0)
			System.out.println("No");
		else
			System.out.println("Yes");
	}

} public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int thp = sc.nextInt();
		int ta = sc.nextInt();
		int ahp = sc.nextInt();
		int aa = sc.nextInt();

		while (thp > 0) {
			ahp -= ta;
			if (ahp <= 0)
				break;
			thp -= aa;
		}
		if (thp <= 0)
			System.out.println("No");
		else
			System.out.println("Yes");
	}

} Main


import java.util.Scanner;

public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int thp = sc.nextInt();
		int ta = sc.nextInt();
		int ahp = sc.nextInt();
		int aa = sc.nextInt();

		while (thp > 0) {
			ahp -= ta;
			if (ahp <= 0)
				break;
			thp -= aa;
		}
		if (thp <= 0)
			System.out.println("No");
		else
			System.out.println("Yes");
	}

}
