import math
import decimal

def zeta(n):
    if n==2:
        return math.pi**2/6-1
    elif n==3:
        return 0.202056903159594
    else:
        ret=decimal.Decimal(0)
        for i in range(2,100):
            ret+=decimal.Decimal(1)/decimal.Decimal(i**n)
        return ret

n=int(input())
if n>=100:
    print(0)
else:
    ans=decimal.Decimal(0)
    for i in range(n,300):
        ans+=zeta(i)
    print(int(ans*(10**6)))