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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
int main(void){
char s[105];scanf("%s",s);
char ss[15]="keyence";
int um=0;
int wrong=0;
int mistakes=0;
for(int i=0;s[i]!='\0'||ss[i]!='\0';i++){
    if(s[i]==ss[um]&&wrong>0){um++;mistakes++;wrong=0;}
    else if(s[i]==ss[um]){um++;}
    else{wrong++;}

    if(mistakes>=2){printf("NO\n");return 0;}
}
if(um<=5){printf("NO\n");return 0;}
printf("YES\n");
}