Problem:
Euler's Phi Function

For given integer n, count the totatives of n, that is, the positive integers less than or equal to n that are relatively prime to n.

Input

n

An integer n (1 ≤ n ≤ 1000000000).

Output

The number of totatives in a line.

Sample Input 1

6

Sample Output 1

2

Sample Input 2

1000000

Sample Output 2

400000

Solution in Python3 (judge verdict: Accepted)

n = num = int(input())
i=2
while i * i <= n:
    if n % i ==0:
        num = num // i * (i - 1)
        while n % i == 0:
            n //= i
    i += 1
if n != 1 :
    num = num // n * (n - 1)
print(num)