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;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            var input = Console.ReadLine();

            var keyence = "keyence";

            if (input == keyence)
            {
                Console.WriteLine("YES");
                return;
            }

            var result = false;

            for (int keyenceIndex = 0; keyenceIndex < keyence.Length; keyenceIndex++)
            {
                var frontResult = false;
                var backResult = false;
                if (keyenceIndex == 0)
                {
                    frontResult = Regex.IsMatch(input, $".+{keyence}\\b|\\b{keyence}.+");
                    backResult = true;
                }
                //途中に文字列が入る時
                else if (frontResult = Regex.IsMatch(input, $"\\b{keyence.Substring(0, keyenceIndex)}.+"))
                {
                    //後半側の末尾が空白
                    backResult = Regex.IsMatch(input, $".+{keyence.Substring(keyenceIndex)}\\b");
                }

                if (frontResult && backResult)
                {
                    result = true;
                    break;
                }
            }

            if (result)
            {
                Console.WriteLine("YES");
            }
            else
            {
                Console.WriteLine("NO");
            }
        }
    }
}