import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A, B, C, D;

		A = sc.nextInt();
		B = sc.nextInt();
		C = sc.nextInt();
		D = sc.nextInt();

		int l,m;
		if(C%B==0) l=C/B;
		else l=C/B+1;
		
		if(A%D==0) m=A/D;
		else m=A/D+1;
		if (l<=m)
			System.out.println("Yes");
		else
			System.out.println("No");

	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A, B, C, D;

		A = sc.nextInt();
		B = sc.nextInt();
		C = sc.nextInt();
		D = sc.nextInt();

		int l,m;
		if(C%B==0) l=C/B;
		else l=C/B+1;
		
		if(A%D==0) m=A/D;
		else m=A/D+1;
		if (l<=m)
			System.out.println("Yes");
		else
			System.out.println("No");

	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A, B, C, D;

		A = sc.nextInt();
		B = sc.nextInt();
		C = sc.nextInt();
		D = sc.nextInt();

		int l,m;
		if(C%B==0) l=C/B;
		else l=C/B+1;
		
		if(A%D==0) m=A/D;
		else m=A/D+1;
		if (l<=m)
			System.out.println("Yes");
		else
			System.out.println("No");

	} main {
		Scanner sc = new Scanner(System.in);
		int A, B, C, D;

		A = sc.nextInt();
		B = sc.nextInt();
		C = sc.nextInt();
		D = sc.nextInt();

		int l,m;
		if(C%B==0) l=C/B;
		else l=C/B+1;
		
		if(A%D==0) m=A/D;
		else m=A/D+1;
		if (l<=m)
			System.out.println("Yes");
		else
			System.out.println("No");

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int A A B B C C D; D A = sc.nextInt() A sc.nextInt() sc.nextInt sc B = sc.nextInt() B sc.nextInt() sc.nextInt sc C = sc.nextInt() C sc.nextInt() sc.nextInt sc D = sc.nextInt() D sc.nextInt() sc.nextInt sc int l l m; m if(C%B==0) l=C/B;
		else l=C/B+1; C%B==0 C%B C B 0 l=C/B l C/B C B l=C/B+1 l C/B+1 C/B C B 1 if(A%D==0) m=A/D;
		else m=A/D+1; A%D==0 A%D A D 0 m=A/D m A/D A D m=A/D+1 m A/D+1 A/D A D 1 if (l<=m)
			System.out.println("Yes");
		else
			System.out.println("No"); l<=m l m System.out.println("Yes") System.out.println System.out System System.out "Yes" System.out.println("No") System.out.println System.out System System.out "No" String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A, B, C, D;

		A = sc.nextInt();
		B = sc.nextInt();
		C = sc.nextInt();
		D = sc.nextInt();

		int l,m;
		if(C%B==0) l=C/B;
		else l=C/B+1;
		
		if(A%D==0) m=A/D;
		else m=A/D+1;
		if (l<=m)
			System.out.println("Yes");
		else
			System.out.println("No");

	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A, B, C, D;

		A = sc.nextInt();
		B = sc.nextInt();
		C = sc.nextInt();
		D = sc.nextInt();

		int l,m;
		if(C%B==0) l=C/B;
		else l=C/B+1;
		
		if(A%D==0) m=A/D;
		else m=A/D+1;
		if (l<=m)
			System.out.println("Yes");
		else
			System.out.println("No");

	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A, B, C, D;

		A = sc.nextInt();
		B = sc.nextInt();
		C = sc.nextInt();
		D = sc.nextInt();

		int l,m;
		if(C%B==0) l=C/B;
		else l=C/B+1;
		
		if(A%D==0) m=A/D;
		else m=A/D+1;
		if (l<=m)
			System.out.println("Yes");
		else
			System.out.println("No");

	}
}
