The cows have just learned what a primitive root is! Given a prime p, a primitive root is an integer x (1 \le x \lt p) such that none of integers x-1,x2-1,...,xp-2-1 are divisible by p, but xp-1-1 is. Unfortunately, computing primitive roots can be time consuming, so the cows need your help. Given a prime p, help the cows find the number of primitive roots .

Input The input contains a single line containing an integer p (2 \le p \lt 2000). It is guaranteed that p is a prime.

Output Output on a single line the number of primitive roots .

The only primitive root is 2.The primitive roots are 2 and 3.