import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner scan = new Scanner(System.in);
		
		int a = scan.nextInt();
		int b = scan.nextInt();
		int c = scan.nextInt();
		int d = scan.nextInt();
		
		boolean judge = false;
		
		while(true) {
			c -= b;
			if(c <= 0 ) {
				judge = true;
				break;
			}
			
			a -= d;
			if(a <= 0 ) {
				judge = false;
				break;
			}
		}
		
		if( judge == true) {
			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) {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner scan = new Scanner(System.in);
		
		int a = scan.nextInt();
		int b = scan.nextInt();
		int c = scan.nextInt();
		int d = scan.nextInt();
		
		boolean judge = false;
		
		while(true) {
			c -= b;
			if(c <= 0 ) {
				judge = true;
				break;
			}
			
			a -= d;
			if(a <= 0 ) {
				judge = false;
				break;
			}
		}
		
		if( judge == true) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}
	}

} Main public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner scan = new Scanner(System.in);
		
		int a = scan.nextInt();
		int b = scan.nextInt();
		int c = scan.nextInt();
		int d = scan.nextInt();
		
		boolean judge = false;
		
		while(true) {
			c -= b;
			if(c <= 0 ) {
				judge = true;
				break;
			}
			
			a -= d;
			if(a <= 0 ) {
				judge = false;
				break;
			}
		}
		
		if( judge == true) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}
	} main {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner scan = new Scanner(System.in);
		
		int a = scan.nextInt();
		int b = scan.nextInt();
		int c = scan.nextInt();
		int d = scan.nextInt();
		
		boolean judge = false;
		
		while(true) {
			c -= b;
			if(c <= 0 ) {
				judge = true;
				break;
			}
			
			a -= d;
			if(a <= 0 ) {
				judge = false;
				break;
			}
		}
		
		if( judge == true) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int a = scan.nextInt(); a scan.nextInt() scan.nextInt scan int b = scan.nextInt(); b scan.nextInt() scan.nextInt scan int c = scan.nextInt(); c scan.nextInt() scan.nextInt scan int d = scan.nextInt(); d scan.nextInt() scan.nextInt scan boolean judge = false; judge false while(true) {
			c -= b;
			if(c <= 0 ) {
				judge = true;
				break;
			}
			
			a -= d;
			if(a <= 0 ) {
				judge = false;
				break;
			}
		} true {
			c -= b;
			if(c <= 0 ) {
				judge = true;
				break;
			}
			
			a -= d;
			if(a <= 0 ) {
				judge = false;
				break;
			}
		} c -= b c b if(c <= 0 ) {
				judge = true;
				break;
			} c <= 0 c 0 {
				judge = true;
				break;
			} judge = true judge true break; a -= d a d if(a <= 0 ) {
				judge = false;
				break;
			} a <= 0 a 0 {
				judge = false;
				break;
			} judge = false judge false break; if( judge == true) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		} judge == true judge true {
			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" String[] args args public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner scan = new Scanner(System.in);
		
		int a = scan.nextInt();
		int b = scan.nextInt();
		int c = scan.nextInt();
		int d = scan.nextInt();
		
		boolean judge = false;
		
		while(true) {
			c -= b;
			if(c <= 0 ) {
				judge = true;
				break;
			}
			
			a -= d;
			if(a <= 0 ) {
				judge = false;
				break;
			}
		}
		
		if( judge == true) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}
	}

} public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner scan = new Scanner(System.in);
		
		int a = scan.nextInt();
		int b = scan.nextInt();
		int c = scan.nextInt();
		int d = scan.nextInt();
		
		boolean judge = false;
		
		while(true) {
			c -= b;
			if(c <= 0 ) {
				judge = true;
				break;
			}
			
			a -= d;
			if(a <= 0 ) {
				judge = false;
				break;
			}
		}
		
		if( judge == true) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}
	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner scan = new Scanner(System.in);
		
		int a = scan.nextInt();
		int b = scan.nextInt();
		int c = scan.nextInt();
		int d = scan.nextInt();
		
		boolean judge = false;
		
		while(true) {
			c -= b;
			if(c <= 0 ) {
				judge = true;
				break;
			}
			
			a -= d;
			if(a <= 0 ) {
				judge = false;
				break;
			}
		}
		
		if( judge == true) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}
	}

}
