#!/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