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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

namespace atcorder_keyence_2019
{
    class Program
    {
        static void Main(string[] args)
        {
            string line = Console.ReadLine();

            string ret = "NO";
            if(
                (Regex.IsMatch(line, "keyence$"))
                ||
                (Regex.IsMatch(line, "^keyence"))
                ||
                ((Regex.IsMatch(line, "^k")) && (Regex.IsMatch(line, "eyence$")))
                ||
                ((Regex.IsMatch(line, "^ke")) && (Regex.IsMatch(line, "yence$")))
                ||
                ((Regex.IsMatch(line, "^key")) && (Regex.IsMatch(line, "ence$")))
                ||
                ((Regex.IsMatch(line, "^keye")) && (Regex.IsMatch(line, "nce$")))
                ||
                ((Regex.IsMatch(line, "^keyen")) && (Regex.IsMatch(line, "ce$")))
                ||
                ((Regex.IsMatch(line, "^keyenc")) && (Regex.IsMatch(line, "e$")))      
            )
            {
                ret = "YES";
            }

            Console.WriteLine(ret);
        }
    }
}