#include <bits/stdc++.h>

using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
int n;

inline int phi(int n) {
    int rez = n, d = 2;
    while(n > 1) {
        if(n % d == 0) {
            rez = rez / d * (d - 1);
            while(n % d == 0) n /= d;
        }
        d++;
        if(d * d > n) d = n;
    }
    return rez;
}

int main()
{
    fin >> n;
    fout << phi(n);

    return 0;
}