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A. Cows and Primitive Roots

time limit per test

2 secondsmemory limit per test

256 megabytesinput

standard inputoutput

standard outputThe 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, *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 .

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.

Codeforces (c) Copyright 2010-2017 Mike Mirzayanov

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