Package for this problem was not updated by the problem writer or Codeforces administration after we’ve upgraded the judging servers. To adjust the time limit constraint, solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then value 800 ms will be displayed and used to determine the verdict.

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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 2010-2021 Mike Mirzayanov

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