Problem:
Score : 200 points

Problem Statement

A string is called a KEYENCE string when it can be changed to keyence by removing its contiguous substring (possibly empty) only once.

Given a string S consisting of lowercase English letters, determine if S is a KEYENCE string.

Constraints

The length of S is between 7 and 100 (inclusive).

S consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

S

Output

If S is a KEYENCE string, print YES; otherwise, print NO.

Sample Input 1

keyofscience

Sample Output 1

YES

keyence is an abbreviation of key of science.

Sample Input 2

mpyszsbznf

Sample Output 2

NO

Sample Input 3

ashlfyha

Sample Output 3

NO

Sample Input 4

keyence

Sample Output 4

YES

Solution in Ruby (2.3.3) (judge verdict: Wrong Answer)

s = gets.chomp
k = []

s.split("").each do |c|
  if c == "k"
    k = []
    k.push(c)
  elsif !k.empty?
    two = k[-2]
    if two.nil?
      if c == 'e'
        k.push(c)
      end
    else
      last = k[-2..-1]
      case last
      when %w(k e)
        k.push(c) if c == "y"
      when %w(e y)
        k.push(c) if c == "e"
      when %w(y e)
        k.push(c) if c == "n"
      when %w(e n)
        k.push(c) if c == "c"
      when %w(n c)
        k.push(c) if c == "e"

        puts("YES")
        exit
      end
    end
  end
end

puts("NO")