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.Linq;
using System.Collections.Generic;
using System.Numerics;
namespace AtCoder
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var inp = Inputer.CharArray().ToList();
            bool flg = false;
            
            for(int i= 0; i < inp.Count; i++)
            {
                for (int j = i;j< inp.Count-i;j++)
                {
                    var check = new List<Char>(inp);
                    check.RemoveRange(i,j);
                    if(string.Join("",check) == "keyence")
                    {
                        flg = true;
                    }

                }
                
            }
            Console.Write(flg ? "YES" : "NO");
        }





    }


    /// <summary>
    /// 素数かどうか判定する
    /// </summary>
    static class IsPrime
    {
        /// <summary>
        /// 素数かどうか判定
        /// </summary>
        /// <param name="num"></param>
        /// <returns></returns>
        public static bool Is(int num)
        {
            if (num < 2) return false;
            else if (num == 2) return true;
            else if (num % 2 == 0) return false;

            double sqrtNum = Math.Sqrt(num);
            for (int i = 3; i <= sqrtNum; i += 2)
            {
                if (num % i == 0)
                {

                    return false;
                }
            }


            return true;
        }

    }

    /// <summary>
    /// 入力受付
    /// </summary>
    static class Inputer
    {
        /// <summary>
        /// A B C の複数整数からなる1行を受け取る
        /// </summary>
        /// <returns></returns>
        public static int[] IntArray1Line()
        {
            return Console.ReadLine().Split().Select(int.Parse).ToArray();
        }

        /// <summary>
        /// 整数N　のような１つの整数からなる入力を受け取る
        /// </summary>
        /// <returns></returns>
        public static int Int1Char()
        {
            return int.Parse(Console.ReadLine());
        }

        /// <summary>
        /// 大きい整数N　のような１つの整数からなる入力を受け取る
        /// </summary>
        /// <returns></returns>
        public static long Long1Char()
        {
            return long.Parse(Console.ReadLine());

        }

        public static List<int> MultLineInt(int Linenum)
        {
            var L = new List<int>();
            for(int i = 0; i < Linenum; i++)
            {
                L.Add(int.Parse(Console.ReadLine()));
            }
            return L;
        } 

        public static long[] LongArray1Line()
        {
            return Console.ReadLine().Split().Select(long.Parse).ToArray();
        }

        public static Char[] CharArray()
        {
            return Console.ReadLine().ToCharArray();
        }

    }

    /// <summary>
    /// 順列を出すやつ
    /// </summary>
    /// <typeparam name="T"></typeparam>
    static class Permutation<T>
    {
        private static void Search(List<T[]> perms, Stack<T> stack, T[] a)
        {
            int N = a.Length;
            if (N == 0)
            {
                perms.Add(stack.Reverse().ToArray());
            }
            else
            {
                var b = new T[N - 1];
                Array.Copy(a, 1, b, 0, N - 1);
                for (int i = 0; i < a.Length; ++i)
                {
                    stack.Push(a[i]);
                    Search(perms, stack, b);
                    if (i < b.Length) { b[i] = a[i]; }
                    stack.Pop();
                }
            }
        }
        public static IEnumerable<T[]> All(IEnumerable<T> src)
        {
            var perms = new List<T[]>();
            Search(perms, new Stack<T>(), src.ToArray());
            return perms;
        }
    }
    
    /// <summary>
    /// 素因数分解
    /// </summary>
    static class PrimeFactors
    {
        public static IEnumerable<long> PrimeFactor(long n)
        {
            long i = 2;
            long tmp = n;

            while (i * i <= n) 
            {
                if (tmp % i == 0)
                {
                    tmp /= i;
                    yield return i;
                }
                else
                {
                    i++;
                }
            }
            if (tmp != 1) yield return tmp;//最後の素数も返す
        }

    }

}