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: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Numerics;
using System.Diagnostics;

class Program
{
    public void Slove()
    {
        string input = Console.ReadLine();
        string judgeStr = "keyence";
        bool result = false;
        foreach(int i in Enumerable.Range(0, input.Length))
        {
            if(input[i] == judgeStr[0])
            {
                int end = 0;
                for(; end < input.Length && input[end + i] == judgeStr[end]; end++)
                {
                }
                if(end == judgeStr.Length)
                {
                    result = true;
                    break;
                }
                //Console.WriteLine(input[end]);
                //Console.WriteLine(string.Join("",judgeStr.Skip(end)));
                result =
                    Enumerable.Range(0, input.Length - end)
                    .Skip(end)
                    .Select(x => input.Skip(x).Take(judgeStr.Length - end))
                    //.Select(x => { Console.WriteLine(string.Join("",x)); return x;})
                    .Any(str => str.SequenceEqual(judgeStr.Skip(end)));
                if(result)
                    break;
            }
            if(result)
                break;
        }
        Console.WriteLine(result ? "YES" : "NO");
    }
    static void Main(string[] args)
    {
        var p = new Program();
        p.Slove();
    }
}