#include <iostream>
using namespace std;

int phi (int n) {
    int res = n;
    for (int d = 2; d * d <= n; d++) {
        if (n % d == 0) {
            res = res / d * (d - 1);
            while (n % d == 0)
                n /= d;
        }
    }
    if (n > 1) res = res / n * (n - 1);
    return res;
}

int main () {
    int k;
    while (cin >> k) {
        cout << phi (k) << endl;
    }
    return 0;
}