import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();

		while (true) {

			c = c - b;
			if (c <= 0) {
				System.out.println("Yes");
				break;
			}

			a = a - d;
			if (a <= 0) {
				System.out.println("No");
				break;
			}
		}

		sc.close();

	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();

		while (true) {

			c = c - b;
			if (c <= 0) {
				System.out.println("Yes");
				break;
			}

			a = a - d;
			if (a <= 0) {
				System.out.println("No");
				break;
			}
		}

		sc.close();

	}
} Main public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();

		while (true) {

			c = c - b;
			if (c <= 0) {
				System.out.println("Yes");
				break;
			}

			a = a - d;
			if (a <= 0) {
				System.out.println("No");
				break;
			}
		}

		sc.close();

	} main {

		Scanner sc = new Scanner(System.in);

		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();

		while (true) {

			c = c - b;
			if (c <= 0) {
				System.out.println("Yes");
				break;
			}

			a = a - d;
			if (a <= 0) {
				System.out.println("No");
				break;
			}
		}

		sc.close();

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc int c = sc.nextInt(); c sc.nextInt() sc.nextInt sc int d = sc.nextInt(); d sc.nextInt() sc.nextInt sc while (true) {

			c = c - b;
			if (c <= 0) {
				System.out.println("Yes");
				break;
			}

			a = a - d;
			if (a <= 0) {
				System.out.println("No");
				break;
			}
		} true {

			c = c - b;
			if (c <= 0) {
				System.out.println("Yes");
				break;
			}

			a = a - d;
			if (a <= 0) {
				System.out.println("No");
				break;
			}
		} c = c - b c c - b c b if (c <= 0) {
				System.out.println("Yes");
				break;
			} c <= 0 c 0 {
				System.out.println("Yes");
				break;
			} System.out.println("Yes") System.out.println System.out System System.out "Yes" break; a = a - d a a - d a d if (a <= 0) {
				System.out.println("No");
				break;
			} a <= 0 a 0 {
				System.out.println("No");
				break;
			} System.out.println("No") System.out.println System.out System System.out "No" break; sc.close() sc.close sc String[] args args public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();

		while (true) {

			c = c - b;
			if (c <= 0) {
				System.out.println("Yes");
				break;
			}

			a = a - d;
			if (a <= 0) {
				System.out.println("No");
				break;
			}
		}

		sc.close();

	}
} public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();

		while (true) {

			c = c - b;
			if (c <= 0) {
				System.out.println("Yes");
				break;
			}

			a = a - d;
			if (a <= 0) {
				System.out.println("No");
				break;
			}
		}

		sc.close();

	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();

		while (true) {

			c = c - b;
			if (c <= 0) {
				System.out.println("Yes");
				break;
			}

			a = a - d;
			if (a <= 0) {
				System.out.println("No");
				break;
			}
		}

		sc.close();

	}
}