from math import pi, floor

def zeta_m1(n):
    if n == 2:
        return pi*pi/6 - 1.0
    elif n == 3:
        return 0.202056903159594
    elif n == 4:
        return pi**4/90 - 1.0
    res = 0
    for i in range(2, 1000):
        denom = i ** n
        if denom > 1e18:
            break
        res += 1 / denom
    return res

X = int(input())
ans = 0
for i in range(X, 50000):
    ans += zeta_m1(i)

print(int(floor(ans*1000000)))