import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int hpa = sc.nextInt(), ata = sc.nextInt(), hpb = sc.nextInt(), atb = sc.nextInt();

		while(true) {
			hpb -= ata;
			if(hpb <= 0) {
				System.out.println("Yes");
				break;
			}
			hpa -= atb;
			if(hpa <= 0) {
				System.out.println("No");
				break;
			}
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int hpa = sc.nextInt(), ata = sc.nextInt(), hpb = sc.nextInt(), atb = sc.nextInt();

		while(true) {
			hpb -= ata;
			if(hpb <= 0) {
				System.out.println("Yes");
				break;
			}
			hpa -= atb;
			if(hpa <= 0) {
				System.out.println("No");
				break;
			}
		}
	}
} Main public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int hpa = sc.nextInt(), ata = sc.nextInt(), hpb = sc.nextInt(), atb = sc.nextInt();

		while(true) {
			hpb -= ata;
			if(hpb <= 0) {
				System.out.println("Yes");
				break;
			}
			hpa -= atb;
			if(hpa <= 0) {
				System.out.println("No");
				break;
			}
		}
	} main {

		Scanner sc = new Scanner(System.in);

		int hpa = sc.nextInt(), ata = sc.nextInt(), hpb = sc.nextInt(), atb = sc.nextInt();

		while(true) {
			hpb -= ata;
			if(hpb <= 0) {
				System.out.println("Yes");
				break;
			}
			hpa -= atb;
			if(hpa <= 0) {
				System.out.println("No");
				break;
			}
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int hpa = sc.nextInt() hpa sc.nextInt() sc.nextInt sc ata = sc.nextInt() ata sc.nextInt() sc.nextInt sc hpb = sc.nextInt() hpb sc.nextInt() sc.nextInt sc atb = sc.nextInt(); atb sc.nextInt() sc.nextInt sc while(true) {
			hpb -= ata;
			if(hpb <= 0) {
				System.out.println("Yes");
				break;
			}
			hpa -= atb;
			if(hpa <= 0) {
				System.out.println("No");
				break;
			}
		} true {
			hpb -= ata;
			if(hpb <= 0) {
				System.out.println("Yes");
				break;
			}
			hpa -= atb;
			if(hpa <= 0) {
				System.out.println("No");
				break;
			}
		} hpb -= ata hpb ata if(hpb <= 0) {
				System.out.println("Yes");
				break;
			} hpb <= 0 hpb 0 {
				System.out.println("Yes");
				break;
			} System.out.println("Yes") System.out.println System.out System System.out "Yes" break; hpa -= atb hpa atb if(hpa <= 0) {
				System.out.println("No");
				break;
			} hpa <= 0 hpa 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 sc = new Scanner(System.in);

		int hpa = sc.nextInt(), ata = sc.nextInt(), hpb = sc.nextInt(), atb = sc.nextInt();

		while(true) {
			hpb -= ata;
			if(hpb <= 0) {
				System.out.println("Yes");
				break;
			}
			hpa -= atb;
			if(hpa <= 0) {
				System.out.println("No");
				break;
			}
		}
	}
} public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int hpa = sc.nextInt(), ata = sc.nextInt(), hpb = sc.nextInt(), atb = sc.nextInt();

		while(true) {
			hpb -= ata;
			if(hpb <= 0) {
				System.out.println("Yes");
				break;
			}
			hpa -= atb;
			if(hpa <= 0) {
				System.out.println("No");
				break;
			}
		}
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int hpa = sc.nextInt(), ata = sc.nextInt(), hpb = sc.nextInt(), atb = sc.nextInt();

		while(true) {
			hpb -= ata;
			if(hpb <= 0) {
				System.out.println("Yes");
				break;
			}
			hpa -= atb;
			if(hpa <= 0) {
				System.out.println("No");
				break;
			}
		}
	}
}