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 (
	"bufio"
	"fmt"
	"os"
	"sort"
)

var (
	read  = bufio.NewReader(os.Stdin)
	write = bufio.NewWriter(os.Stdout)
)

func min(a, b int) int {
	if a <= b {
		return a
	}
	return b
}

func max(a, b int) int {
	if a >= b {
		return a
	}
	return b
}

func yesno(result bool) {
	if result {
		fmt.Fprintln(write, "Yes")
	} else {
		fmt.Fprintln(write, "No")
	}
}

func printansStr(result bool, a, b string) {
	if result {
		fmt.Fprintln(write, a)
	} else {
		fmt.Fprintln(write, b)
	}
}

func printansInt(result bool, a, b int) {
	if result {
		fmt.Fprintln(write, a)
	} else {
		fmt.Fprintln(write, b)
	}
}

func main() {
	defer write.Flush()

	var n, m int
	fmt.Fscan(read, &n, &m)

	a := make([]int, n)
	sum := 0
	for i := range a {
		fmt.Fscan(read, &a[i])
		sum += a[i]
	}
	sort.Sort(sort.Reverse(sort.IntSlice(a)))

	if a[m-1]*4*m < sum {
		fmt.Fprintln(write, "No")
	} else {
		fmt.Fprintln(write, "Yes")
	}
}