import sys, time
s = time.time()
sys.setrecursionlimit(2147483647)
input = lambda:sys.stdin.readline().rstrip()
def resolve():
    n = int(input())
    ans = 0
    i = 1
    while time.time() - s < 1.8:
        ans += 1 / pow(i, n)
        i += 1
    print(ans)
resolve()