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 = C-B;
			if(C > 0) {
				A = A-D;
			}
		}while (A > 0 && C > 0);
				
		if(A > C) {
			System.out.println("Yes");
		}else{
			System.out.println("No");
		}
		
		sc.close();
	}
} 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 = C-B;
			if(C > 0) {
				A = A-D;
			}
		}while (A > 0 && C > 0);
				
		if(A > C) {
			System.out.println("Yes");
		}else{
			System.out.println("No");
		}
		
		sc.close();
	}
} 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 = C-B;
			if(C > 0) {
				A = A-D;
			}
		}while (A > 0 && C > 0);
				
		if(A > C) {
			System.out.println("Yes");
		}else{
			System.out.println("No");
		}
		
		sc.close();
	} 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 = C-B;
			if(C > 0) {
				A = A-D;
			}
		}while (A > 0 && C > 0);
				
		if(A > C) {
			System.out.println("Yes");
		}else{
			System.out.println("No");
		}
		
		sc.close();
	} 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 = C-B;
			if(C > 0) {
				A = A-D;
			}
		}while (A > 0 && C > 0); A > 0 && C > 0 A > 0 A 0 C > 0 C 0 {
			C = C-B;
			if(C > 0) {
				A = A-D;
			}
		} C = C-B C C-B C B if(C > 0) {
				A = A-D;
			} C > 0 C 0 {
				A = A-D;
			} A = A-D A A-D A D if(A > C) {
			System.out.println("Yes");
		}else{
			System.out.println("No");
		} A > C A C {
			System.out.println("Yes");
		} System.out.println("Yes") System.out.println System.out System System.out "Yes" {
			System.out.println("No");
		} System.out.println("No") System.out.println System.out System System.out "No" sc.close() sc.close sc 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 = C-B;
			if(C > 0) {
				A = A-D;
			}
		}while (A > 0 && C > 0);
				
		if(A > C) {
			System.out.println("Yes");
		}else{
			System.out.println("No");
		}
		
		sc.close();
	}
} 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 = C-B;
			if(C > 0) {
				A = A-D;
			}
		}while (A > 0 && C > 0);
				
		if(A > C) {
			System.out.println("Yes");
		}else{
			System.out.println("No");
		}
		
		sc.close();
	}
} 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 = C-B;
			if(C > 0) {
				A = A-D;
			}
		}while (A > 0 && C > 0);
				
		if(A > C) {
			System.out.println("Yes");
		}else{
			System.out.println("No");
		}
		
		sc.close();
	}
}