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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>

int partition(int a[], int p, int r){
  int x, i, j, t;
  x = a[r];
  i = p - 1;
  for(j=p; j<r; j++){
    if(a[j] <= x){
      i++;
      t = a[i];
      a[i] = a[j];
      a[j] = t;
    }
  }
  t = a[i+1];
  a[i+1] = a[r];
  a[r] = t;
  return i+1;
}

void quickSort(int a[],int p, int r){
  int q;
  if(p < r){
    q = partition(a, p, r);
    quickSort(a, p, q-1);
    quickSort(a, q+1, r);
  }
}

int main(){
  int n, m;
  scanf("%d%d", &n, &m);
  int i;
  int sum = 0;
  int a[n];
  for(i=0; i<n; i++){
    scanf("%d", &a[i]);
    sum += a[i];
  }
  quickSort(a, 0, n-1);
  
  if (a[n - 1 - m] < (sum / (4 * m)))
    printf("No\n");
  else
    printf("Yes\n");
}