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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;
using ll= long long;
using vi= vector<int>;
using vvi= vector<vi>;
using vd= vector<double>;
using vvd= vector<vd>;
using vc= vector<char>;
using vb= vector<bool>;
using vl= vector<ll>;
#define rep(i,x,n) for(int i=x; i<n; i++)
#define all(x) x.begin(), x.end()

int main(void){
  int n;
  double m,vote=0;
  cin>>n>>m;
  vi a(n);
  rep(i,0,n){
    cin>>a[i];
    vote+=a[i];
  }
  sort(all(a));
  
  if(a[n-m]<(double)vote/4/m){
    cout << "No";
  }else{
    cout << "Yes";
  }
  
  return 0;
}