def f(n):
    for i in range(2, 8192 + 1):
        x = i ** n
        if x > 1000000000:
            break
        t.append(1 / x)


x = int(input())

t = []
for i in range(x, 64):
    f(i)

t.extend([0] * (64 * 8192 - len(t)))
t.sort()

x = 1
while x < 64 * 8192:
    for i in range(0, 64 * 8192, x * 2):
        t[i] += t[i + x]
    x *= 2

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