import java.util.Scanner;

public class Main {
	static int A;
	static int B;
	static int C;
	static int D;
	static int a=0;
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		A=sc.nextInt();
		B=sc.nextInt();
		C=sc.nextInt();
		D=sc.nextInt();
		fight();
	}
	static void fight() {
		C=C-B;
		if(C<=0) {
			System.out.println("Yes");
		}
		else {
			A=A-D;
			if(A<=0) {
				System.out.println("No");
			}
			else {
				fight();
			}
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	static int A;
	static int B;
	static int C;
	static int D;
	static int a=0;
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		A=sc.nextInt();
		B=sc.nextInt();
		C=sc.nextInt();
		D=sc.nextInt();
		fight();
	}
	static void fight() {
		C=C-B;
		if(C<=0) {
			System.out.println("Yes");
		}
		else {
			A=A-D;
			if(A<=0) {
				System.out.println("No");
			}
			else {
				fight();
			}
		}
	}
} Main static int A; A static int B; B static int C; C static int D; D static int a=0; a 0 public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		A=sc.nextInt();
		B=sc.nextInt();
		C=sc.nextInt();
		D=sc.nextInt();
		fight();
	} main {
		Scanner sc=new Scanner(System.in);
		A=sc.nextInt();
		B=sc.nextInt();
		C=sc.nextInt();
		D=sc.nextInt();
		fight();
	} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) 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 fight() fight String[] args args static void fight() {
		C=C-B;
		if(C<=0) {
			System.out.println("Yes");
		}
		else {
			A=A-D;
			if(A<=0) {
				System.out.println("No");
			}
			else {
				fight();
			}
		}
	} fight {
		C=C-B;
		if(C<=0) {
			System.out.println("Yes");
		}
		else {
			A=A-D;
			if(A<=0) {
				System.out.println("No");
			}
			else {
				fight();
			}
		}
	} C=C-B C C-B C B if(C<=0) {
			System.out.println("Yes");
		}
		else {
			A=A-D;
			if(A<=0) {
				System.out.println("No");
			}
			else {
				fight();
			}
		} C<=0 C 0 {
			System.out.println("Yes");
		} System.out.println("Yes") System.out.println System.out System System.out "Yes" {
			A=A-D;
			if(A<=0) {
				System.out.println("No");
			}
			else {
				fight();
			}
		} A=A-D A A-D A D if(A<=0) {
				System.out.println("No");
			}
			else {
				fight();
			} A<=0 A 0 {
				System.out.println("No");
			} System.out.println("No") System.out.println System.out System System.out "No" {
				fight();
			} fight() fight public class Main {
	static int A;
	static int B;
	static int C;
	static int D;
	static int a=0;
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		A=sc.nextInt();
		B=sc.nextInt();
		C=sc.nextInt();
		D=sc.nextInt();
		fight();
	}
	static void fight() {
		C=C-B;
		if(C<=0) {
			System.out.println("Yes");
		}
		else {
			A=A-D;
			if(A<=0) {
				System.out.println("No");
			}
			else {
				fight();
			}
		}
	}
} public class Main {
	static int A;
	static int B;
	static int C;
	static int D;
	static int a=0;
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		A=sc.nextInt();
		B=sc.nextInt();
		C=sc.nextInt();
		D=sc.nextInt();
		fight();
	}
	static void fight() {
		C=C-B;
		if(C<=0) {
			System.out.println("Yes");
		}
		else {
			A=A-D;
			if(A<=0) {
				System.out.println("No");
			}
			else {
				fight();
			}
		}
	}
} Main
import java.util.Scanner;

public class Main {
	static int A;
	static int B;
	static int C;
	static int D;
	static int a=0;
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		A=sc.nextInt();
		B=sc.nextInt();
		C=sc.nextInt();
		D=sc.nextInt();
		fight();
	}
	static void fight() {
		C=C-B;
		if(C<=0) {
			System.out.println("Yes");
		}
		else {
			A=A-D;
			if(A<=0) {
				System.out.println("No");
			}
			else {
				fight();
			}
		}
	}
}