import java.util.Scanner;

public class Main
{
	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		sc.close();
		String ans="Yes";
		while(true) {
			if (c-b>0) {
				c= c-b;
				if (a-d>0) {
					a=a-d;
				} else {
					ans = "No";
					break;
				}
			} else {
				break;
			}
		}
		System.out.println(ans);
	}
} import java.util.Scanner; Scanner java.util public class Main
{
	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		sc.close();
		String ans="Yes";
		while(true) {
			if (c-b>0) {
				c= c-b;
				if (a-d>0) {
					a=a-d;
				} else {
					ans = "No";
					break;
				}
			} else {
				break;
			}
		}
		System.out.println(ans);
	}
} Main public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		sc.close();
		String ans="Yes";
		while(true) {
			if (c-b>0) {
				c= c-b;
				if (a-d>0) {
					a=a-d;
				} else {
					ans = "No";
					break;
				}
			} else {
				break;
			}
		}
		System.out.println(ans);
	} main {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		sc.close();
		String ans="Yes";
		while(true) {
			if (c-b>0) {
				c= c-b;
				if (a-d>0) {
					a=a-d;
				} else {
					ans = "No";
					break;
				}
			} else {
				break;
			}
		}
		System.out.println(ans);
	} 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 sc.close() sc.close sc String ans="Yes"; ans "Yes" while(true) {
			if (c-b>0) {
				c= c-b;
				if (a-d>0) {
					a=a-d;
				} else {
					ans = "No";
					break;
				}
			} else {
				break;
			}
		} true {
			if (c-b>0) {
				c= c-b;
				if (a-d>0) {
					a=a-d;
				} else {
					ans = "No";
					break;
				}
			} else {
				break;
			}
		} if (c-b>0) {
				c= c-b;
				if (a-d>0) {
					a=a-d;
				} else {
					ans = "No";
					break;
				}
			} else {
				break;
			} c-b>0 c-b c b 0 {
				c= c-b;
				if (a-d>0) {
					a=a-d;
				} else {
					ans = "No";
					break;
				}
			} c= c-b c c-b c b if (a-d>0) {
					a=a-d;
				} else {
					ans = "No";
					break;
				} a-d>0 a-d a d 0 {
					a=a-d;
				} a=a-d a a-d a d {
					ans = "No";
					break;
				} ans = "No" ans "No" break; {
				break;
			} break; System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main
{
	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		sc.close();
		String ans="Yes";
		while(true) {
			if (c-b>0) {
				c= c-b;
				if (a-d>0) {
					a=a-d;
				} else {
					ans = "No";
					break;
				}
			} else {
				break;
			}
		}
		System.out.println(ans);
	}
} public class Main
{
	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		sc.close();
		String ans="Yes";
		while(true) {
			if (c-b>0) {
				c= c-b;
				if (a-d>0) {
					a=a-d;
				} else {
					ans = "No";
					break;
				}
			} else {
				break;
			}
		}
		System.out.println(ans);
	}
} Main
import java.util.Scanner;

public class Main
{
	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();
		sc.close();
		String ans="Yes";
		while(true) {
			if (c-b>0) {
				c= c-b;
				if (a-d>0) {
					a=a-d;
				} else {
					ans = "No";
					break;
				}
			} else {
				break;
			}
		}
		System.out.println(ans);
	}
}
