def f(n):
    t = [0] * 8192
    for i in range(1, 8192 + 1):
        x = i ** n
        if x > 1000000000:
            break
        t[i - 1] = 1 / x
    x = 1
    while x < 8192:
        for i in range(0, 8192, x * 2):
            t[i] += t[i + x]
        x *= 2
    return t[0]


x = int(input())

t = [0] * 1024
for i in range(x, 1024 + 1):
    t[i - 1] = f(i) - 1

x = 1
while x < 1024:
    for i in range(0, 1024, x * 2):
        t[i] += t[i + x]
    x *= 2

print(int(t[0] * (10 ** 6)))