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 Go (1.6) (judge verdict: Wrong Answer)

package main

import (
  "fmt"
  "sort"
)

func main() {
  var n, m int
	fmt.Scanf("%d %d", &n, &m)
	v := make([]int, n)
	for i := range v {
		fmt.Scan(&v[i])
	}

	sort.Sort(sort.Reverse(sort.IntSlice(v)))
	r := 0
	for _, i := range v {
		r = r + i
	}
	l := r / (m * 4)
	var a string
	if v[m-1] > l {
		a = "Yes"
	} else {
		a = "No"
	}
	fmt.Println(a)
}