Problem:
Score : 200 points

Problem Statement

Takahashi and Aoki will have a battle using their monsters.

The health and strength of Takahashi's monster are A and B, respectively, and those of Aoki's monster are C and D, respectively.

The two monsters will take turns attacking, in the order Takahashi's, Aoki's, Takahashi's, Aoki's, ...
Here, an attack decreases the opponent's health by the value equal to the attacker's strength.
The monsters keep attacking until the health of one monster becomes 0 or below. The person with the monster whose health becomes 0 or below loses, and the other person wins.

If Takahashi will win, print Yes; if he will lose, print No.

Constraints

1 \leq A,B,C,D \leq 100

All values in input are integers.

Input

Input is given from Standard Input in the following format:

A B C D

Output

If Takahashi will win, print Yes; if he will lose, print No.

Sample Input 1

10 9 10 10

Sample Output 1

No

First, Takahashi's monster attacks Aoki's monster, whose health is now 10-9=1.

Next, Aoki's monster attacks Takahashi's monster, whose health is now 10-10=0.

Takahashi's monster is the first to have 0 or less health, so Takahashi loses.

Sample Input 2

46 4 40 5

Sample Output 2

Yes

Solution in Scala (2.13.1) (judge verdict: Accepted)

import java.util.Scanner

object Main extends App {
  val sc = new Scanner(System.in)

  val a = sc.nextInt                 // 入力Aを受け付けて、aに格納する
  val b = sc.nextInt                 // 入力Bを受け付けて、bに格納する
  val c = sc.nextInt                 // 入力Cを受け付けて、cに格納する
  val d = sc.nextInt
  //println(((k+a-1)/a)*a)
  val n = (x:Int, y:Int)=>(x+y-1)/y
  val res = if(n(a,d)>=n(c,b))"Yes"else"No"

  println(res)                       // 結果を出力する
}