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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<iostream>
#include<string>
#include <algorithm>

using namespace std;

int main() {
    string s;
    cin >> s;

    int keyence_i = 6;
    string keyence_s = "keyence";
    string creating = "";
    int deleted_i = -1;

    for(int i = (s.size() - 1); i >= 0; --i) {
        if (keyence_s[keyence_i] == s[i]) {
            creating += s[i];
            keyence_i--;
        } else {
            if (deleted_i != -1 && deleted_i - 1 != i) {
                cout << "NO" << endl;
                return 0;
            };
            deleted_i = i;
        }
    }

    reverse(creating.begin(), creating.end());
    if (creating == keyence_s) cout << "YES" << endl;
    else cout << "NO" << endl;

    return 0;
}