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: Accepted)

package main

import (
	"fmt"
	"sort"
)

func main() {
	var n, m, j int
	arr := make([]int, 0)
	total := 0
	fmt.Scanf("%d %d\n", &n, &m)
	for i := 0; i < n; i++ {
		fmt.Scanf("%d", &j)
		arr = append(arr, j)
		total += j
	}
	// popular := total / (4 * m)
	sort.Sort(sort.Reverse(sort.IntSlice(arr)))
	// flag := true
	// for i := 0; i < m; i++ {
	// 	if arr[i] < popular {
	// 		flag = false
	// 		break
	// 	}
	// }
	if arr[m-1]*4*m >= total {
		fmt.Println("Yes")
	} else {
		fmt.Println("No")
	}
}