import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int a = scan.nextInt();
		int b = scan.nextInt();
		int c = scan.nextInt();
		int d = scan.nextInt();
		
		while (a > 0 && c > 0) {
			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 scan = new Scanner(System.in);
		int a = scan.nextInt();
		int b = scan.nextInt();
		int c = scan.nextInt();
		int d = scan.nextInt();
		
		while (a > 0 && c > 0) {
			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 scan = new Scanner(System.in);
		int a = scan.nextInt();
		int b = scan.nextInt();
		int c = scan.nextInt();
		int d = scan.nextInt();
		
		while (a > 0 && c > 0) {
			c -= b;
			if (c <= 0) {
				System.out.println("Yes");
				break;
			}
			a -= d;
			if (a <= 0) {
				System.out.println("No");
				break;
			}
		}
	} main {
		Scanner scan = new Scanner(System.in);
		int a = scan.nextInt();
		int b = scan.nextInt();
		int c = scan.nextInt();
		int d = scan.nextInt();
		
		while (a > 0 && c > 0) {
			c -= b;
			if (c <= 0) {
				System.out.println("Yes");
				break;
			}
			a -= d;
			if (a <= 0) {
				System.out.println("No");
				break;
			}
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int a = scan.nextInt(); a scan.nextInt() scan.nextInt scan int b = scan.nextInt(); b scan.nextInt() scan.nextInt scan int c = scan.nextInt(); c scan.nextInt() scan.nextInt scan int d = scan.nextInt(); d scan.nextInt() scan.nextInt scan while (a > 0 && c > 0) {
			c -= b;
			if (c <= 0) {
				System.out.println("Yes");
				break;
			}
			a -= d;
			if (a <= 0) {
				System.out.println("No");
				break;
			}
		} a > 0 && c > 0 a > 0 a 0 c > 0 c 0 {
			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 scan = new Scanner(System.in);
		int a = scan.nextInt();
		int b = scan.nextInt();
		int c = scan.nextInt();
		int d = scan.nextInt();
		
		while (a > 0 && c > 0) {
			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 scan = new Scanner(System.in);
		int a = scan.nextInt();
		int b = scan.nextInt();
		int c = scan.nextInt();
		int d = scan.nextInt();
		
		while (a > 0 && c > 0) {
			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 scan = new Scanner(System.in);
		int a = scan.nextInt();
		int b = scan.nextInt();
		int c = scan.nextInt();
		int d = scan.nextInt();
		
		while (a > 0 && c > 0) {
			c -= b;
			if (c <= 0) {
				System.out.println("Yes");
				break;
			}
			a -= d;
			if (a <= 0) {
				System.out.println("No");
				break;
			}
		}
	}
}