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 JavaScript (judge verdict: Time Limit Exceeded)

function Main(input) {
    var n = parseInt(input, 10);
    var count = 0;
    for (i = 1; i < n; i++) {
        if (gcd(n, i) == 1) count++;
    }
    console.log(count);
}

function gcd(n, m) {
    var a, b, c;
    a = Math.max(n, m);
    b = Math.min(n, m);
    c = a % b; 
    if (c == 0) {
        return b;
    } else {
        return gcd(b, c);
    }
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));