146. Euler's Totient
MediumTotient
Print φ(n): how many integers in 1..n are coprime with n.
Input format
A single integer n.
Output format
φ(n)
Example 1
Input
9
Output
6
Example 2
Input
1
Output
1
Constraints
1 ≤ n ≤ 10¹²
Read input from standard input and print the answer to standard output. Your code is judged against 5 test cases, most of them hidden.
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