#include <cstdio>

#include <cstring>

#include <cstdlib>

#include <iostream>

#include <algorithm>

#include <cmath>

#define N 10010

using namespace std;

int get_phi(int n)

{

    int m = sqrt(n+0.5);

    int ans = n;

    for (int i = ; i <= m; ++i)

        if (n % i == )

        {

            ans = ans / i * (i-);

            while (n % i == ) n /= i;

        }

    if (n > ) ans = ans / n * (n-);

    return ans;

}

int main()

{

    int n;

    scanf("%d", &n);

    printf("%d\n", get_phi(n));

}