def factorize(x):
    ret = []
    p = 2
    while p * p <= x:
        cnt = 0
        while x % p == 0:
            x //= p
            cnt += 1
        if cnt:
            ret.append(p)
        p += 1
    if x > 1:
        ret.append(x)
    return ret

n = int(input())
ps = factorize(n)
k = len(ps)
ans = 1
for s in range(1, 1 << k):
    p = 1
    for i in range(k):
        if s >> i & 1:
            p *= ps[i]
    cnt = n // p
    # p = cnt / n
    # p/(1-p) = cnt / (n - cnt)
    v = cnt / (n - cnt)
    if s.bit_count() % 2:
        ans += v
    else:
        ans -= v
print(f'{ans:.12f}')