import java.util.*;
public class Main {
	public static void main(String[] args)  {
		Scanner scan = new Scanner(System.in);
		int a = Integer.parseInt(scan.next());
		int b = Integer.parseInt(scan.next());
		int c = Integer.parseInt(scan.next());
		int d = Integer.parseInt(scan.next());

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

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

	}

}
//end import java.util.*; util.* java public class Main {
	public static void main(String[] args)  {
		Scanner scan = new Scanner(System.in);
		int a = Integer.parseInt(scan.next());
		int b = Integer.parseInt(scan.next());
		int c = Integer.parseInt(scan.next());
		int d = Integer.parseInt(scan.next());

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

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

	}

} Main public static void main(String[] args)  {
		Scanner scan = new Scanner(System.in);
		int a = Integer.parseInt(scan.next());
		int b = Integer.parseInt(scan.next());
		int c = Integer.parseInt(scan.next());
		int d = Integer.parseInt(scan.next());

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

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

	} main {
		Scanner scan = new Scanner(System.in);
		int a = Integer.parseInt(scan.next());
		int b = Integer.parseInt(scan.next());
		int c = Integer.parseInt(scan.next());
		int d = Integer.parseInt(scan.next());

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

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

	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int a = Integer.parseInt(scan.next()); a Integer.parseInt(scan.next()) Integer.parseInt Integer scan.next() scan.next scan int b = Integer.parseInt(scan.next()); b Integer.parseInt(scan.next()) Integer.parseInt Integer scan.next() scan.next scan int c = Integer.parseInt(scan.next()); c Integer.parseInt(scan.next()) Integer.parseInt Integer scan.next() scan.next scan int d = Integer.parseInt(scan.next()); d Integer.parseInt(scan.next()) Integer.parseInt Integer scan.next() scan.next scan while(true){
			c -=b;
			if(c <= 0){
				System.out.println("Yes");
				break;
			}

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

			a -=d;
			if(a <= 0){
				System.out.print("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.print("No");
				break;
			} a <= 0 a 0 {
				System.out.print("No");
				break;
			} System.out.print("No") System.out.print 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 = Integer.parseInt(scan.next());
		int b = Integer.parseInt(scan.next());
		int c = Integer.parseInt(scan.next());
		int d = Integer.parseInt(scan.next());

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

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

	}

} public class Main {
	public static void main(String[] args)  {
		Scanner scan = new Scanner(System.in);
		int a = Integer.parseInt(scan.next());
		int b = Integer.parseInt(scan.next());
		int c = Integer.parseInt(scan.next());
		int d = Integer.parseInt(scan.next());

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

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

	}

} Main
import java.util.*;
public class Main {
	public static void main(String[] args)  {
		Scanner scan = new Scanner(System.in);
		int a = Integer.parseInt(scan.next());
		int b = Integer.parseInt(scan.next());
		int c = Integer.parseInt(scan.next());
		int d = Integer.parseInt(scan.next());

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

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

	}

}
//end