### Irreducible Basic Fractions

Time Limit: 1000 ms Memory Limit: 65536 KiB

#### Problem Description

A fraction is called basic, when m / n s.t. 0<=m<n; A fraction is called irreducible, when gcd(m, n)=1;
Now given a number n, and you are to find out the number of fractions (basic irreducible fractions) with the denominator of n.

#### Input

Multiple input cases, and each with a single number n.

#### Sample Input

12

#### Sample Output

4

#### Hint

0/12, 1/12, 2/12, 3/12, 4/12, 5/12, 6/12, 7/12, 8/12, 9/12, 10/12, 11/12.
=>
1/12, 5/12, 7/12, 11/12
=>4

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