import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A = Integer.parseInt(sc.next());
		int B = Integer.parseInt(sc.next());
		int C = Integer.parseInt(sc.next());
		int D = Integer.parseInt(sc.next());
		sc.close();

		while (true) {
			C -= B;
			if (C <= 0) {
				System.out.println("Yes");
				break;
			}
			A -= D;
			if (A <= 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 A = Integer.parseInt(sc.next());
		int B = Integer.parseInt(sc.next());
		int C = Integer.parseInt(sc.next());
		int D = Integer.parseInt(sc.next());
		sc.close();

		while (true) {
			C -= B;
			if (C <= 0) {
				System.out.println("Yes");
				break;
			}
			A -= D;
			if (A <= 0) {
				System.out.println("No");
				break;
			}
		}

	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A = Integer.parseInt(sc.next());
		int B = Integer.parseInt(sc.next());
		int C = Integer.parseInt(sc.next());
		int D = Integer.parseInt(sc.next());
		sc.close();

		while (true) {
			C -= B;
			if (C <= 0) {
				System.out.println("Yes");
				break;
			}
			A -= D;
			if (A <= 0) {
				System.out.println("No");
				break;
			}
		}

	} main {
		Scanner sc = new Scanner(System.in);
		int A = Integer.parseInt(sc.next());
		int B = Integer.parseInt(sc.next());
		int C = Integer.parseInt(sc.next());
		int D = Integer.parseInt(sc.next());
		sc.close();

		while (true) {
			C -= B;
			if (C <= 0) {
				System.out.println("Yes");
				break;
			}
			A -= D;
			if (A <= 0) {
				System.out.println("No");
				break;
			}
		}

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int A = Integer.parseInt(sc.next()); A Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int B = Integer.parseInt(sc.next()); B Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int C = Integer.parseInt(sc.next()); C Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int D = Integer.parseInt(sc.next()); D Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc sc.close() sc.close sc while (true) {
			C -= B;
			if (C <= 0) {
				System.out.println("Yes");
				break;
			}
			A -= D;
			if (A <= 0) {
				System.out.println("No");
				break;
			}
		} true {
			C -= B;
			if (C <= 0) {
				System.out.println("Yes");
				break;
			}
			A -= D;
			if (A <= 0) {
				System.out.println("No");
				break;
			}
		} 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 -= 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; String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A = Integer.parseInt(sc.next());
		int B = Integer.parseInt(sc.next());
		int C = Integer.parseInt(sc.next());
		int D = Integer.parseInt(sc.next());
		sc.close();

		while (true) {
			C -= B;
			if (C <= 0) {
				System.out.println("Yes");
				break;
			}
			A -= D;
			if (A <= 0) {
				System.out.println("No");
				break;
			}
		}

	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A = Integer.parseInt(sc.next());
		int B = Integer.parseInt(sc.next());
		int C = Integer.parseInt(sc.next());
		int D = Integer.parseInt(sc.next());
		sc.close();

		while (true) {
			C -= B;
			if (C <= 0) {
				System.out.println("Yes");
				break;
			}
			A -= D;
			if (A <= 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 A = Integer.parseInt(sc.next());
		int B = Integer.parseInt(sc.next());
		int C = Integer.parseInt(sc.next());
		int D = Integer.parseInt(sc.next());
		sc.close();

		while (true) {
			C -= B;
			if (C <= 0) {
				System.out.println("Yes");
				break;
			}
			A -= D;
			if (A <= 0) {
				System.out.println("No");
				break;
			}
		}

	}

}