A. Cows and Primitive Roots
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

The cows have just learned what a primitive root is! Given a prime p, a primitive root is an integer x (1 ≤ x < 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 ≤ p < 2000). It is guaranteed that p is a prime.

Output

Output on a single line the number of primitive roots .

Examples
Input
3
Output
1
Input
5
Output
2
Note

The only primitive root is 2.

The primitive roots are 2 and 3.