Largest Prime Finder

In this problem, you are given an integer ( n ) and you need to find the largest prime number that is less than or equal to ( n ). A prime number is defined as a natural number greater than 1 that has no positive divisors other than 1 and itself (i.e. ( p > 1 ) and its only divisors are 1 and ( p )). If there is no prime number that meets the criteria, output None.

inputFormat

The input consists of a single integer ( n ) provided via standard input.

outputFormat

Output the largest prime number less than or equal to ( n ). If no such prime exists, output None (without quotes).## sample

10

7