Next, we want to teach our censored calculator to check if numbers are primes or not. This crazy calculator has learned new some words (but forgotten some others) and does not accept new words, certain symbols and it hates digits!

The list of forbidden words and symbols:

- import
- div
- eval
- range
- len
- ⁄ % −
- digits (0-9)

Given a number (0 < n < 10000), you should check if it is a prime or not. Your solution should not contain any of the forbidden words, symbols or digits (even as a part of another word).

**Input: ** A number as an integer.

**Output: ** Is it prime or not as a boolean.

**Example:**

checkio(5) == True checkio(18) == False

**How it is used: **
Challenge your creativity and come up with a solution to fit this mission's specs!

**Precondition:** 1 < number < 10000