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 PHP7 (7.0.15) (judge verdict: Wrong Answer)

<?php

$input = trim(fgets(STDIN));
$input = str_split($input);

$ans = ['k', 'e', 'y', 'e', 'n', 'c', 'e'];

$inputNum = 0;
$ansNum = 0;

$chance = FALSE;
$creepingUp = FALSE;

foreach($input as $val){
    if($ansNum < count($ans) && $input[$inputNum] == $ans[$ansNum]){
        if($chance){
            $creepingUp = TRUE;
        }
        $inputNum++;
        $ansNum++;
    }elseif($creepingUp){
        echo "NO";
        exit;
    }else{
        $chance = TRUE;
        $inputNum++;
    }
}

if ($ansNum != count($ans)) {
    echo "NO";
    exit;
}

echo "YES";
exit;