import java.util.Scanner;

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

		int tLife = scanner.nextInt();
		int tAttack = scanner.nextInt();
		int aLife = scanner.nextInt();
		int aAttack = scanner.nextInt();

		while (true) {
			aLife -= tAttack;

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

			tLife -= aAttack;
			if (tLife <= 0) {
				System.out.println("No");
				break;
			}
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);

		int tLife = scanner.nextInt();
		int tAttack = scanner.nextInt();
		int aLife = scanner.nextInt();
		int aAttack = scanner.nextInt();

		while (true) {
			aLife -= tAttack;

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

			tLife -= aAttack;
			if (tLife <= 0) {
				System.out.println("No");
				break;
			}
		}
	}
} Main public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);

		int tLife = scanner.nextInt();
		int tAttack = scanner.nextInt();
		int aLife = scanner.nextInt();
		int aAttack = scanner.nextInt();

		while (true) {
			aLife -= tAttack;

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

			tLife -= aAttack;
			if (tLife <= 0) {
				System.out.println("No");
				break;
			}
		}
	} main {
		Scanner scanner = new Scanner(System.in);

		int tLife = scanner.nextInt();
		int tAttack = scanner.nextInt();
		int aLife = scanner.nextInt();
		int aAttack = scanner.nextInt();

		while (true) {
			aLife -= tAttack;

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

			tLife -= aAttack;
			if (tLife <= 0) {
				System.out.println("No");
				break;
			}
		}
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int tLife = scanner.nextInt(); tLife scanner.nextInt() scanner.nextInt scanner int tAttack = scanner.nextInt(); tAttack scanner.nextInt() scanner.nextInt scanner int aLife = scanner.nextInt(); aLife scanner.nextInt() scanner.nextInt scanner int aAttack = scanner.nextInt(); aAttack scanner.nextInt() scanner.nextInt scanner while (true) {
			aLife -= tAttack;

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

			tLife -= aAttack;
			if (tLife <= 0) {
				System.out.println("No");
				break;
			}
		} true {
			aLife -= tAttack;

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

			tLife -= aAttack;
			if (tLife <= 0) {
				System.out.println("No");
				break;
			}
		} aLife -= tAttack aLife tAttack if (aLife <= 0) {
				System.out.println("Yes");
				break;
			} aLife <= 0 aLife 0 {
				System.out.println("Yes");
				break;
			} System.out.println("Yes") System.out.println System.out System System.out "Yes" break; tLife -= aAttack tLife aAttack if (tLife <= 0) {
				System.out.println("No");
				break;
			} tLife <= 0 tLife 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 scanner = new Scanner(System.in);

		int tLife = scanner.nextInt();
		int tAttack = scanner.nextInt();
		int aLife = scanner.nextInt();
		int aAttack = scanner.nextInt();

		while (true) {
			aLife -= tAttack;

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

			tLife -= aAttack;
			if (tLife <= 0) {
				System.out.println("No");
				break;
			}
		}
	}
} public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);

		int tLife = scanner.nextInt();
		int tAttack = scanner.nextInt();
		int aLife = scanner.nextInt();
		int aAttack = scanner.nextInt();

		while (true) {
			aLife -= tAttack;

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

			tLife -= aAttack;
			if (tLife <= 0) {
				System.out.println("No");
				break;
			}
		}
	}
} Main
import java.util.Scanner;

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

		int tLife = scanner.nextInt();
		int tAttack = scanner.nextInt();
		int aLife = scanner.nextInt();
		int aAttack = scanner.nextInt();

		while (true) {
			aLife -= tAttack;

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

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