import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int t_HP = Integer.parseInt(sc.next());
		int t_atk = Integer.parseInt(sc.next());
		int a_HP = Integer.parseInt(sc.next());
		int a_atk = Integer.parseInt(sc.next());

		while (true) {
			a_HP -= t_atk;
			if (a_HP <= 0) {
				System.out.println("Yes");
				break;
			}

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

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

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int t_HP = Integer.parseInt(sc.next());
		int t_atk = Integer.parseInt(sc.next());
		int a_HP = Integer.parseInt(sc.next());
		int a_atk = Integer.parseInt(sc.next());

		while (true) {
			a_HP -= t_atk;
			if (a_HP <= 0) {
				System.out.println("Yes");
				break;
			}

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

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int t_HP = Integer.parseInt(sc.next());
		int t_atk = Integer.parseInt(sc.next());
		int a_HP = Integer.parseInt(sc.next());
		int a_atk = Integer.parseInt(sc.next());

		while (true) {
			a_HP -= t_atk;
			if (a_HP <= 0) {
				System.out.println("Yes");
				break;
			}

			t_HP -= a_atk;
			if (t_HP <= 0) {
				System.out.println("No");
				break;
			}
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int t_HP = Integer.parseInt(sc.next());
		int t_atk = Integer.parseInt(sc.next());
		int a_HP = Integer.parseInt(sc.next());
		int a_atk = Integer.parseInt(sc.next());

		while (true) {
			a_HP -= t_atk;
			if (a_HP <= 0) {
				System.out.println("Yes");
				break;
			}

			t_HP -= a_atk;
			if (t_HP <= 0) {
				System.out.println("No");
				break;
			}
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int t_HP = Integer.parseInt(sc.next()); t_HP Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int t_atk = Integer.parseInt(sc.next()); t_atk Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int a_HP = Integer.parseInt(sc.next()); a_HP Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int a_atk = Integer.parseInt(sc.next()); a_atk Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc while (true) {
			a_HP -= t_atk;
			if (a_HP <= 0) {
				System.out.println("Yes");
				break;
			}

			t_HP -= a_atk;
			if (t_HP <= 0) {
				System.out.println("No");
				break;
			}
		} true {
			a_HP -= t_atk;
			if (a_HP <= 0) {
				System.out.println("Yes");
				break;
			}

			t_HP -= a_atk;
			if (t_HP <= 0) {
				System.out.println("No");
				break;
			}
		} a_HP -= t_atk a_HP t_atk if (a_HP <= 0) {
				System.out.println("Yes");
				break;
			} a_HP <= 0 a_HP 0 {
				System.out.println("Yes");
				break;
			} System.out.println("Yes") System.out.println System.out System System.out "Yes" break; t_HP -= a_atk t_HP a_atk if (t_HP <= 0) {
				System.out.println("No");
				break;
			} t_HP <= 0 t_HP 0 {
				System.out.println("No");
				break;
			} System.out.println("No") System.out.println System.out System System.out "No" break; String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int t_HP = Integer.parseInt(sc.next());
		int t_atk = Integer.parseInt(sc.next());
		int a_HP = Integer.parseInt(sc.next());
		int a_atk = Integer.parseInt(sc.next());

		while (true) {
			a_HP -= t_atk;
			if (a_HP <= 0) {
				System.out.println("Yes");
				break;
			}

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

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int t_HP = Integer.parseInt(sc.next());
		int t_atk = Integer.parseInt(sc.next());
		int a_HP = Integer.parseInt(sc.next());
		int a_atk = Integer.parseInt(sc.next());

		while (true) {
			a_HP -= t_atk;
			if (a_HP <= 0) {
				System.out.println("Yes");
				break;
			}

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

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int t_HP = Integer.parseInt(sc.next());
		int t_atk = Integer.parseInt(sc.next());
		int a_HP = Integer.parseInt(sc.next());
		int a_atk = Integer.parseInt(sc.next());

		while (true) {
			a_HP -= t_atk;
			if (a_HP <= 0) {
				System.out.println("Yes");
				break;
			}

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

}
