import java.io.File;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		//task b battle
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt(); int b =sc.nextInt(); int c = sc.nextInt(); int d = sc.nextInt();
		boolean turn = true;
		while(a>0&&c>0){
			if(turn){
				c-=b;
			}else{
				a-=d;
			}
			turn= !turn;
		}
		System.out.println(a>0?"Yes":"No");

	}
} import java.io.File; File java.io import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		//task b battle
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt(); int b =sc.nextInt(); int c = sc.nextInt(); int d = sc.nextInt();
		boolean turn = true;
		while(a>0&&c>0){
			if(turn){
				c-=b;
			}else{
				a-=d;
			}
			turn= !turn;
		}
		System.out.println(a>0?"Yes":"No");

	}
} Main public static void main(String[] args) {
		//task b battle
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt(); int b =sc.nextInt(); int c = sc.nextInt(); int d = sc.nextInt();
		boolean turn = true;
		while(a>0&&c>0){
			if(turn){
				c-=b;
			}else{
				a-=d;
			}
			turn= !turn;
		}
		System.out.println(a>0?"Yes":"No");

	} main {
		//task b battle
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt(); int b =sc.nextInt(); int c = sc.nextInt(); int d = sc.nextInt();
		boolean turn = true;
		while(a>0&&c>0){
			if(turn){
				c-=b;
			}else{
				a-=d;
			}
			turn= !turn;
		}
		System.out.println(a>0?"Yes":"No");

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b =sc.nextInt(); b sc.nextInt() sc.nextInt sc int c = sc.nextInt(); c sc.nextInt() sc.nextInt sc int d = sc.nextInt(); d sc.nextInt() sc.nextInt sc boolean turn = true; turn true while(a>0&&c>0){
			if(turn){
				c-=b;
			}else{
				a-=d;
			}
			turn= !turn;
		} a>0&&c>0 a>0 a 0 c>0 c 0 {
			if(turn){
				c-=b;
			}else{
				a-=d;
			}
			turn= !turn;
		} if(turn){
				c-=b;
			}else{
				a-=d;
			} turn {
				c-=b;
			} c-=b c b {
				a-=d;
			} a-=d a d turn= !turn turn !turn turn System.out.println(a>0?"Yes":"No") System.out.println System.out System System.out a>0?"Yes":"No" a>0 a 0 "Yes" "No" String[] args args public class Main {
	public static void main(String[] args) {
		//task b battle
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt(); int b =sc.nextInt(); int c = sc.nextInt(); int d = sc.nextInt();
		boolean turn = true;
		while(a>0&&c>0){
			if(turn){
				c-=b;
			}else{
				a-=d;
			}
			turn= !turn;
		}
		System.out.println(a>0?"Yes":"No");

	}
} public class Main {
	public static void main(String[] args) {
		//task b battle
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt(); int b =sc.nextInt(); int c = sc.nextInt(); int d = sc.nextInt();
		boolean turn = true;
		while(a>0&&c>0){
			if(turn){
				c-=b;
			}else{
				a-=d;
			}
			turn= !turn;
		}
		System.out.println(a>0?"Yes":"No");

	}
} Main
import java.io.File;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		//task b battle
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt(); int b =sc.nextInt(); int c = sc.nextInt(); int d = sc.nextInt();
		boolean turn = true;
		while(a>0&&c>0){
			if(turn){
				c-=b;
			}else{
				a-=d;
			}
			turn= !turn;
		}
		System.out.println(a>0?"Yes":"No");

	}
}
