The cows have just learned what a primitive root is! Given a prime p, a primitive root $\operatorname{mod} p$ is an integer x (1 ≤ x < p) such that none of integers x - 1, x^2 - 1, ..., x^{p} - 2 - 1 are divisible by p, but x^{p} - 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 $\operatorname{mod} p$.

-----Input-----

The input contains a single line containing an integer p (2 ≤ p < 2000). It is guaranteed that p is a prime.

-----Output-----

Output on a single line the number of primitive roots $\operatorname{mod} p$.

-----Examples-----

Input 3

Output 1

Input 5

Output 2

-----Note-----

The only primitive root $\operatorname{mod} 3$ is 2.

The primitive roots $\operatorname{mod} 5$ are 2 and 3.