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 <bits/stdc++.h>
using namespace std;

using ll = long long;
using ull = unsigned long long;

#define MOD 1000000007

int main(void) {
    string keyence = "keyence";
    bool flag = false;
    ll current = 0;
    ll c2 = 0;
    string S;
    cin >> S;
    for(auto &c: S) {
        if(c == keyence[current]) {
            flag = false;
            current++;
        } else {
            if(!flag) {
                flag = true;
                c2++;
                if(c2 > 1) {
                    cout << "NO" << endl;
                    return 0;
                }
            }
        }
    }
    if(current == 7) cout << "YES" << endl;
    else cout << "NO" << endl;
    return 0;
}