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;

namespace B___KEYENCE_String
{
    class Program
    {
        static void Main (string[] args)
        {
            var s = Console.ReadLine ();
            var k = "keyence";
            var l = 0;
            for (var i = 0; i < 7; i++)
            {
                var b = false;
                for (var j = l; j < s.Length; j++)
                {
                    if (k[i] == s[j] && j != s.Length - 1)
                    {
                        l = j + 1;
                        b = true;
                        break;
                    }
                    else if (k[i] == s[j] && i == 6)
                    {
                        Console.WriteLine ("YES");
                        return;
                    }
                }
                if (b == false)
                {
                    Console.WriteLine ("NO");
                    return;
                }
            }
        }
    }
}