Problem:
Score : 200 points

Problem Statement

We have held a popularity poll for N items on sale. Item i received A_i votes.

From these N items, we will select M as popular items. However, we cannot select an item with less than \dfrac{1}{4M} of the total number of votes.

If M popular items can be selected, print Yes; otherwise, print No.

Constraints

1 \leq M \leq N \leq 100

1 \leq A_i \leq 1000

A_i are distinct.

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N M
A_1 ... A_N

Output

If M popular items can be selected, print Yes; otherwise, print No.

Sample Input 1

4 1
5 4 2 1

Sample Output 1

Yes

There were 12 votes in total. The most popular item received 5 votes, and we can select it.

Sample Input 2

3 2
380 19 1

Sample Output 2

No

There were 400 votes in total. The second and third most popular items received less than \dfrac{1}{4\times 2} of the total number of votes, so we cannot select them. Thus, we cannot select two popular items.

Sample Input 3

12 3
4 56 78 901 2 345 67 890 123 45 6 789

Sample Output 3

Yes

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
static class Program
{
	static int[] ReadInts(this TextReader reader) => reader.ReadLine().Split(' ').Select(s => int.Parse(s)).ToArray();
	static IEnumerable<int[]> ReadInts(this TextReader reader, int count)
	{
		for (long i = 0; i < count; ++i)
			yield return reader.ReadInts();
	}

	static IEnumerable<long[]> ReadLongs(this TextReader reader, long count)
	{
		for (long i = 0; i < count; ++i)
			yield return reader.ReadLine().Split(' ').Select(s => long.Parse(s)).ToArray();
	}
	
	public static void Main(string[] args)
	{
		var m = Console.In.ReadInts()[1];
		var a = Console.In.ReadInts();
		var sum = a.Sum();
		var t = sum / (4.0 * m);
		var last = a.OrderByDescending(x => x).Skip(m-1).First();
		Console.WriteLine(last >= t ? "Yes" : "No");
	}
}