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 Haskell (GHC 8.8.3) (judge verdict: Wrong Answer)

import qualified Data.ByteString.Char8 as BS

readString = map BS.unpack . BS.words

getString = readString <$> BS.getLine

calc :: String -> String -> Bool -> Bool -> String
calc [] [] _ _ = "YES"
calc cs [] True True = "NO"
calc cs [] False False = "YES"
calc [] ks _ _ = "NO"
calc (c : cs) (k : ks) False False
  | c == k = calc cs ks False False
  | otherwise = calc cs (k : ks) True False
calc (c : cs) (k : ks) True False
  | c == k = calc cs ks True True
  | otherwise = calc cs (k : ks) True False
calc (c : cs) (k : ks) True True
  | c == k = calc cs ks True True
  | otherwise = "NO"

main = do
  [s] <- getString
  putStrLn $ calc s "keyence" False False