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 Java (OpenJDK 11.0.6) (judge verdict: Accepted)

import java.util.*;
import java.io.*;
 
public class Main {
  public static void main(String[] args) throws Exception{
    FastScanner sc = new FastScanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();
    int d = sc.nextInt();
    
    new Solution(a,b,c,d);
  }
}

class Solution {
  public Solution(int a, int b, int c, int d) {
    int first = (int)((double)c / b) + (c % b == 0 ? 0 : 1);
    int second = (int)((double)a / d) + (a % d == 0 ? 0 : 1);
    if(first <= second) System.out.println("Yes");
    else System.out.println("No");
    // System.out.println(res);
  }
}


class FastScanner {
  private final InputStream in;
  private final byte[] buffer = new byte[1024];
  private int ptr = 0;
  private int buflen = 0;

  public FastScanner(InputStream source) {
    in = source;
  }

  private boolean hasNextByte() {
    if (ptr < buflen) {
      return true;
    } else {
      ptr = 0;
      try {
        buflen = in.read(buffer);
      } catch (IOException e) {
        e.printStackTrace();
      }
      if (buflen <= 0) {
        return false;
      }
    }
    return true;
  }

  private int readByte() {
    if (hasNextByte()) return buffer[ptr++];
    else return -1;
  }

  private static boolean isPrintableChar(int c) {
    return 33 <= c && c <= 126;
  }

  public boolean hasNext() {
    while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
    return hasNextByte();
  }

  public String next() {
    if (!hasNext()) throw new NoSuchElementException();
    StringBuilder sb = new StringBuilder();
    int b = readByte();
    while (isPrintableChar(b)) {
      sb.appendCodePoint(b);
      b = readByte();
    }
    return sb.toString();
  }

  public long nextLong() {
    if (!hasNext()) throw new NoSuchElementException();
    long n = 0;
    boolean minus = false;
    int b = readByte();
    if (b == '-') {
      minus = true;
      b = readByte();
    }
    if (b < '0' || '9' < b) {
      throw new NumberFormatException();
    }
    while (true) {
      if ('0' <= b && b <= '9') {
        n *= 10;
        n += b - '0';
      } else if (b == -1 || !isPrintableChar(b)) {
        return minus ? -n : n;
      } else {
        throw new NumberFormatException();
      }
      b = readByte();
    }
  }

  public int nextInt() {
    long nl = nextLong();
    if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
      throw new NumberFormatException();
    return (int) nl;
  }

  public double nextDouble() {
    return Double.parseDouble(next());
  }
}