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 Ruby (judge verdict: Time Limit Exceeded)

def gcd(x,y)
	while y >0
		r =x%y
		x=y
		y=r
	end
	return x
end


n=gets.chomp.to_i

count=0

for i in 1..n-1
	if gcd(n,i)==1
		count+=1
	end
end
p count