Alex and broken contest

题意翻译

有一天，Alex搞了个比赛，然后手滑把题目列表删了。题目都被保存下来了，但现在他需要在他自己出的所有题中找到它们。 这次比赛中，他出的每一道题目都包含了### 正好一次 他朋友的名字：“Danil”、“Olya”、“Slava”、“Ann”和“Nikita” ，### 区分大小写 但是Anton大佬出的题目太多了，现在要求你写一个程序（他本人应该是懒得写了），来判断这个题目是否属于这次竞赛。 输入输出格式： 输入：一行包，一个含小写字母、大写字母和“_”的字符串，长度<=100。 输出格式： 如果问题是属于这个比赛，输出“YES”，否则输出“NO”（不输出引号）。

题目描述

One day Alex was creating a contest about his friends, but accidentally deleted it. Fortunately, all the problems were saved, but now he needs to find them among other problems. But there are too many problems, to do it manually. Alex asks you to write a program, which will determine if a problem is from this contest by its name. It is known, that problem is from this contest if and only if its name contains one of Alex's friends' name exactly once. His friends' names are "Danil", "Olya", "Slava", "Ann" and "Nikita". Names are case sensitive.

输入输出格式

输入格式

The only line contains string from lowercase and uppercase letters and "\_" symbols of length, not more than $ 100 $ — the name of the problem.

输出格式

Print "YES", if problem is from this contest, and "NO" otherwise.

输入输出样例

输入样例 #1

Alex_and_broken_contest

输出样例 #1

NO

输入样例 #2

NikitaAndString

输出样例 #2

YES

输入样例 #3

Danil_and_Olya

输出样例 #3

NO