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();

		do {
			c -= b;
			if(c <= 0) {
				System.out.print("Yes");
				return;
			}
			else {
				a -= d;
				if(a <= 0) {
					System.out.print("No");
					return;
				}
			}
		}while(a != 0 && c != 0);
	}
} 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();

		do {
			c -= b;
			if(c <= 0) {
				System.out.print("Yes");
				return;
			}
			else {
				a -= d;
				if(a <= 0) {
					System.out.print("No");
					return;
				}
			}
		}while(a != 0 && c != 0);
	}
} 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();

		do {
			c -= b;
			if(c <= 0) {
				System.out.print("Yes");
				return;
			}
			else {
				a -= d;
				if(a <= 0) {
					System.out.print("No");
					return;
				}
			}
		}while(a != 0 && c != 0);
	} main {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int d = sc.nextInt();

		do {
			c -= b;
			if(c <= 0) {
				System.out.print("Yes");
				return;
			}
			else {
				a -= d;
				if(a <= 0) {
					System.out.print("No");
					return;
				}
			}
		}while(a != 0 && c != 0);
	} 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 do {
			c -= b;
			if(c <= 0) {
				System.out.print("Yes");
				return;
			}
			else {
				a -= d;
				if(a <= 0) {
					System.out.print("No");
					return;
				}
			}
		}while(a != 0 && c != 0); a != 0 && c != 0 a != 0 a 0 c != 0 c 0 {
			c -= b;
			if(c <= 0) {
				System.out.print("Yes");
				return;
			}
			else {
				a -= d;
				if(a <= 0) {
					System.out.print("No");
					return;
				}
			}
		} c -= b c b if(c <= 0) {
				System.out.print("Yes");
				return;
			}
			else {
				a -= d;
				if(a <= 0) {
					System.out.print("No");
					return;
				}
			} c <= 0 c 0 {
				System.out.print("Yes");
				return;
			} System.out.print("Yes") System.out.print System.out System System.out "Yes" return; {
				a -= d;
				if(a <= 0) {
					System.out.print("No");
					return;
				}
			} a -= d a d if(a <= 0) {
					System.out.print("No");
					return;
				} a <= 0 a 0 {
					System.out.print("No");
					return;
				} System.out.print("No") System.out.print System.out System System.out "No" return; 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();

		do {
			c -= b;
			if(c <= 0) {
				System.out.print("Yes");
				return;
			}
			else {
				a -= d;
				if(a <= 0) {
					System.out.print("No");
					return;
				}
			}
		}while(a != 0 && c != 0);
	}
} 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();

		do {
			c -= b;
			if(c <= 0) {
				System.out.print("Yes");
				return;
			}
			else {
				a -= d;
				if(a <= 0) {
					System.out.print("No");
					return;
				}
			}
		}while(a != 0 && c != 0);
	}
} 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();

		do {
			c -= b;
			if(c <= 0) {
				System.out.print("Yes");
				return;
			}
			else {
				a -= d;
				if(a <= 0) {
					System.out.print("No");
					return;
				}
			}
		}while(a != 0 && c != 0);
	}
}