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"
    "os"
    "bufio"
    "strconv"
    "sort"
)

var sc = bufio.NewScanner(os.Stdin)

func sum(slice []int) int {
    total := 0
    for _, n := range slice {
        total += n
    }
    return total
}

func main() {
    sc.Split(bufio.ScanWords)

    n, m := nextInt(), nextInt()
    a := nextIntArr(n)
    sortIntsRev(a)

    threshold := sum(a) / (4 * m)

    count := 0
    for _, c := range a{
        if threshold <= c {
            count++
        }
    }

    if count >= m {
        fmt.Println("Yes")
    } else {
        fmt.Println("No")
    }
}


// Library

func nextLine() string {
    sc.Scan()
    return sc.Text()
}

func nextInt() int {
    sc.Scan()
    i, _ := strconv.Atoi(sc.Text())
    return i
}

func nextIntArr(n int) []int {
    var a []int
    for i := 0; i < n; i++ {
        a = append(a, nextInt())
    }
    return a
}

// 数値を桁区切りのスライスにする
func digit(n int, list []int) []int {
   if n > 0 {
       return digit(n/10, append(list, n%10))
   }
   return list
}

func sortIntsRev(list []int) {
    sort.Sort(sort.Reverse(sort.IntSlice(list)))
}

func strReverse(s string) string {
    runes := []rune(s)
    for i := 0; i < len(s)/2; i++ {
        runes[i], runes[len(s)-1-i] = runes[len(s)-1-i], runes[i]
    }
    return string(runes)
}