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 Perl (v5.18.2) (judge verdict: Accepted)

use strict;
use warnings;

chomp(my $nm = <>);
my ($n, $m) = split(/ /, $nm);

chomp(my $input_a = <>);
my @a = split(/ /, $input_a);
my $a_ref = \@a;
@$a_ref = sort {$b <=> $a} @$a_ref;

my $sum;
for my $i (0..$n-1) {
  $sum += $a_ref->[$i];
}

if ($a_ref->[$m-1] >= $sum/(4*$m)) {
  print "Yes\n";
} else {
  print "No\n";
}