from math import pi, floor

X = int(input())

ans = .0
if X == 2:
    ans += (pi ** 2 / 6 - 1) * 10 ** 6
    X += 1
MAX = 10 ** 12
for i in range(X, 30):
    j = 2
    while (y := (j ** i)) < MAX:
        ans += 10 ** 6 / y
        j += 1
print(floor(ans))