#!/usr/bin/env ruby

require 'zipf'

data = []
while line = STDIN.gets
  data << line.to_f
end

data.sort!

k = ARGV[0].to_i

index = (k / 100.0) * data.size

if index.to_i == index
  puts data[index.to_i-1]
else
  puts (data[index.to_i-1] + data[index.to_i]) / 2.0
end