import 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();

	for(int i = 0; i < 100; i++) {
		c -= b;
		if(c <= 0)
		break;
		a -= d;
		if(a <= 0)
		break;
	}
	if(c <= 0)
	System.out.println("Yes");
	else
	System.out.println("No");

	sc.close();
	}
} import java.util.*; util.* java 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();

	for(int i = 0; i < 100; i++) {
		c -= b;
		if(c <= 0)
		break;
		a -= d;
		if(a <= 0)
		break;
	}
	if(c <= 0)
	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();

	for(int i = 0; i < 100; i++) {
		c -= b;
		if(c <= 0)
		break;
		a -= d;
		if(a <= 0)
		break;
	}
	if(c <= 0)
	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();

	for(int i = 0; i < 100; i++) {
		c -= b;
		if(c <= 0)
		break;
		a -= d;
		if(a <= 0)
		break;
	}
	if(c <= 0)
	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 for(int i = 0; i < 100; i++) {
		c -= b;
		if(c <= 0)
		break;
		a -= d;
		if(a <= 0)
		break;
	} int i = 0; int i = 0; i 0 i < 100 i 100 i++ i++ i {
		c -= b;
		if(c <= 0)
		break;
		a -= d;
		if(a <= 0)
		break;
	} {
		c -= b;
		if(c <= 0)
		break;
		a -= d;
		if(a <= 0)
		break;
	} c -= b c b if(c <= 0)
		break; c <= 0 c 0 break; a -= d a d if(a <= 0)
		break; a <= 0 a 0 break; if(c <= 0)
	System.out.println("Yes");
	else
	System.out.println("No"); c <= 0 c 0 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" 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();

	for(int i = 0; i < 100; i++) {
		c -= b;
		if(c <= 0)
		break;
		a -= d;
		if(a <= 0)
		break;
	}
	if(c <= 0)
	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();

	for(int i = 0; i < 100; i++) {
		c -= b;
		if(c <= 0)
		break;
		a -= d;
		if(a <= 0)
		break;
	}
	if(c <= 0)
	System.out.println("Yes");
	else
	System.out.println("No");

	sc.close();
	}
} Main
import 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();

	for(int i = 0; i < 100; i++) {
		c -= b;
		if(c <= 0)
		break;
		a -= d;
		if(a <= 0)
		break;
	}
	if(c <= 0)
	System.out.println("Yes");
	else
	System.out.println("No");

	sc.close();
	}
}