int euler_phi(int n)
{
    int m = (int)sqrt(n + 0.5);
    int ans = n;
    for (int i = 2; i <= m; i++) if (n % i == 0)
    {
        ans = ans / i * (i-1);
        while (n % i == 0) n /= i;
    }
    if (n > 1) ans = ans / n * (n-1);
    return ans;
}
 
int main()
{
    int n;
    while (scanf("%d", &n), n)
        printf("%d\n", n-1-euler_phi(n));
    return 0;
}