[3R2 - Standby for Action](https://www.youtube.com/watch?v=P2ZVC9aoiKo)

Our dear Cafe's owner, JOE Miller, will soon take part in a new game TV-show "1 vs. n"!

The game goes in rounds, where in each round the host asks JOE and his opponents a common question. All participants failing to answer are eliminated. The show ends when only JOE remains (we assume that JOE never answers a question wrong!).

For each question JOE answers, if there are s (s > 0) opponents remaining and t (0 ≤ t ≤ s) of them make a mistake on it, JOE receives \displaystylet/s dollars, and consequently there will be s - t opponents left for the next question.

JOE wonders what is the maximum possible reward he can receive in the best possible scenario. Yet he has little time before show starts, so can you help him answering it instead?

Input

The first and single line contains a single integer n (1 ≤ n ≤ 10^5), denoting the number of JOE's opponents in the show.

Output

Print a number denoting the maximum prize (in dollars) JOE could have.

Your answer will be considered correct if it's absolute or relative error won't exceed 10^{-4}. In other words, if your answer is a and the jury answer is b, then it must hold that (|a - b|)/(max(1, b)) ≤ 10^{-4}.

Examples

Input


1


Output


1.000000000000


Input


2


Output


1.500000000000

Note

In the second example, the best scenario would be: one contestant fails at the first question, the other fails at the next one. The total reward will be \displaystyle 1/2 + 1/1 = 1.5 dollars.
from sys import stdin
from collections import deque
# https://codeforces.com/contest/1354/status/D
mod = 10**9 + 7
import sys
import random
# sys.setrecursionlimit(10**6)
from queue import PriorityQueue
# def rl():
#     return [int(w) for w in stdin.readline().split()]
from bisect import bisect_right
from bisect import bisect_left
from collections import defaultdict
from math import sqrt,factorial,gcd,log2,inf,ceil
# map(int,input().split())
# # l = list(map(int,input().split()))
# from itertools import permutations
import heapq
# input = lambda: sys.stdin.readline().rstrip()
input = lambda : sys.stdin.readline().rstrip()
from sys import stdin, stdout
from heapq import heapify, heappush, heappop
from itertools import permutations
from math import factorial as f

# def ncr(x, y):
#     return f(x) // (f(y) * f(x - y))
def ncr(n, r, p):
    num = den = 1
    for i in range(r):
        num = (num * (n - i)) % p
        den = (den * (i + 1)) % p
    return (num * pow(den,
                      p - 2, p)) % p

import sys

# input = sys.stdin.readline
# LCA
# def bfs(na):
#
#     queue = [na]
#     boo[na] = True
#     level[na] = 0
#
#     while queue!=[]:
#
#         z = queue.pop(0)
#
#         for i in hash[z]:
#
#             if not boo[i]:
#
#                 queue.append(i)
#                 level[i] = level[z] + 1
#                 boo[i] = True
#                 dp[i][0] = z
#
#
#
# def prec(n):
#
#     for i in range(1,20):
#
#         for j in range(1,n+1):
#             if dp[j][i-1]!=-1:
#                 dp[j][i] = dp[dp[j][i-1]][i-1]
#
#
# def lca(u,v):
#     if level[v] < level[u]:
#         u,v = v,u
#
#     diff = level[v] - level[u]
#
#
#     for i in range(20):
#         if ((diff>>i)&1):
#             v = dp[v][i]
#
#
#     if u == v:
#         return u
#
#
#     for i in range(19,-1,-1):
#         # print(i)
#         if dp[u][i] != dp[v][i]:
#
#             u = dp[u][i]
#             v = dp[v][i]
#
#
#     return dp[u][0]
#
# dp = []
#
#
# n = int(input())
#
# for i in range(n + 10):
#
#     ka = [-1]*(20)
#     dp.append(ka)


# class FenwickTree:
#     def __init__(self, x):
#         """transform list into BIT"""
#         self.bit = x
#         for i in range(len(x)):
#             j = i | (i + 1)
#             if j < len(x):
#                 x[j] += x[i]
#
#     def update(self, idx, x):
#         """updates bit[idx] += x"""
#         while idx < len(self.bit):
#             self.bit[idx] += x
#             idx |= idx + 1
#
#     def query(self, end):
#         """calc sum(bit[:end])"""
#         x = 0
#         while end:
#             x += self.bit[end - 1]
#             end &= end - 1
#         return x
#
#     def find_kth_smallest(self, k):
#         """Find largest idx such that sum(bit[:idx]) <= k"""
#         idx = -1
#         for d in reversed(range(len(self.bit).bit_length())):
#             right_idx = idx + (1 << d)
#             if right_idx < len(self.bit) and k >= self.bit[right_idx]:
#                 idx = right_idx
#                 k -= self.bit[idx]
#         return idx + 1



# import sys
# def rs(): return sys.stdin.readline().strip()
# def ri(): return int(sys.stdin.readline())
# def ria(): return list(map(int, sys.stdin.readline().split()))
# def prn(n): sys.stdout.write(str(n))
# def pia(a): sys.stdout.write(' '.join([str(s) for s in a]))
#
#
# import gc, os
#
# ii = 0
# _inp = b''
#
#
# def getchar():
#     global ii, _inp
#     if ii >= len(_inp):
#         _inp = os.read(0, 100000)
#         gc.collect()
#         ii = 0
#     if not _inp:
#         return b' '[0]
#     ii += 1
#     return _inp[ii - 1]
#
#
# def input():
#     c = getchar()
#     if c == b'-'[0]:
#         x = 0
#         sign = 1
#     else:
#         x = c - b'0'[0]
#         sign = 0
#     c = getchar()
#     while c >= b'0'[0]:
#         x = 10 * x + c - b'0'[0]
#         c = getchar()
#     if c == b'\r'[0]:
#         getchar()
#     return -x if sign else x

# fenwick Tree

# n,q = map(int,input().split())
#
#
# l1 = list(map(int,input().split()))
#
# l2 = list(map(int,input().split()))
#
# bit = [0]*(10**6 + 1)
#
# def update(i,add,bit):
#
#     while i>0 and i<len(bit):
#
#         bit[i]+=add
#         i = i + (i&(-i))
#
#
# def sum(i,bit):
#     ans = 0
#     while i>0:
#
#         ans+=bit[i]
#         i = i - (i & ( -i))
#
#
#     return ans
#
# def find_smallest(k,bit):
#
#     l = 0
#     h = len(bit)
#     while l<h:
#
#         mid = (l+h)//2
#         if k <= sum(mid,bit):
#             h = mid
#         else:
#             l = mid + 1
#
#
#     return l
#
#
# def insert(x,bit):
#     update(x,1,bit)
#
# def delete(x,bit):
#     update(x,-1,bit)
# fa = set()
#
# for i in l1:
#     insert(i,bit)
#
#
# for i in l2:
#     if i>0:
#         insert(i,bit)
#
#     else:
#         z = find_smallest(-i,bit)
#
#         delete(z,bit)
#
#
# # print(bit)
# if len(set(bit)) == 1:
#     print(0)
# else:
#     for i in range(1,n+1):
#         z = find_smallest(i,bit)
#         if z!=0:
#             print(z)
#             break
#

# service time problem


# def solve2(s,a,b,hash,z,cnt):
#     temp = cnt.copy()
#     x,y = hash[a],hash[b]
#     i = 0
#     j = len(s)-1
#
#     while z:
#
#         if s[j] - y>=x-s[i]:
#             if temp[s[j]]-1 == 0:
#                 j-=1
#             temp[s[j]]-=1
#             z-=1
#
#
#         else:
#             if temp[s[i]]-1 == 0:
#                 i+=1
#
#             temp[s[i]]-=1
#             z-=1
#
#     return s[i:j+1]
#
#
#
#
#
# def solve1(l,s,posn,z,hash):
#
#     ans = []
#     for i in l:
#         a,b = i
#         ka = solve2(s,a,b,posn,z,hash)
#         ans.append(ka)
#
#         return ans
#
# def consistent(input, window, min_entries, max_entries, tolerance):
#
#     l = input
#     n = len(l)
#     l.sort()
#     s = list(set(l))
#     s.sort()
#
#     if min_entries<=n<=max_entries:
#
#         if s[-1] - s[0]<window:
#             return True
#         hash = defaultdict(int)
#         posn = defaultdict(int)
#         for i in l:
#             hash[i]+=1
#
#         z = (tolerance*(n))//100
#         poss_window = set()
#
#
#         for i in range(len(s)):
#                 posn[i] = l[i]
#                 for j in range(i+1,len(s)):
#                     if s[j]-s[i] == window:
#                         poss_window.add((s[i],s[j]))
#
#         if poss_window!=set():
#             print(poss_window)
#             ans = solve1(poss_window,s,posn,z,hash)
#             print(ans)
#
#
#         else:
#             pass
#
#     else:
#         return False
#
#
#
#
# l = list(map(int,input().split()))
#
# min_ent,max_ent = map(int,input().split())
# w = int(input())
# tol = int(input())
# consistent(l, w, min_ent, max_ent, tol)

# t = int(input())
#
# for i in range(t):
#
#     n,x = map(int,input().split())
#
#     l = list(map(int,input().split()))
#
#     e,o = 0,0
#
#     for i in l:
#         if i%2 == 0:
#             e+=1
#         else:
#             o+=1
#
#     if e+o>=x and o!=0:
#         z = e+o - x
#         if z == 0:
#             if o%2 == 0:
#                 print('No')
#             else:
#                 print('Yes')
#             continue
#         if o%2 == 0:
#             o-=1
#             z-=1
#             if e>=z:
#                 print('Yes')
#             else:
#                 z-=e
#                 o-=z
#                 if o%2!=0:
#                     print('Yes')
#                 else:
#                     print('No')
#
#         else:
#
#             if e>=z:
#                 print('Yes')
#             else:
#                 z-=e
#                 o-=z
#                 if o%2!=0:
#                     print('Yes')
#                 else:
#                     print('No')
#     else:
#         print('No')
#
#
#
#
#
#
#
# def dfs(n):
#     boo[n] = True
#     dp2[n] = 1
#     for i in hash[n]:
#         if not boo[i]:
#
#             dfs(i)
#             dp2[n] += dp2[i]


n = int(input())

ans = 0

for i in range(1,n+1):
    ans += 1/(i)

print(ans)