def main():
    try:
        import pypyjit
        pypyjit.set_param('max_unroll_recursion=-1')
    except:
        pass
    try:
        import sys
        sys.setrecursionlimit(10**7)
    except:
        pass
    from math import sqrt,sin,cos,tan,ceil,radians,floor,gcd,exp,log,log10,log2,factorial,fsum
    from heapq import heapify, heappop, heappush
    from bisect import bisect_left, bisect_right
    from copy import deepcopy
    import copy
    import random
    from collections import deque,Counter,defaultdict
    from itertools import permutations,combinations
    from decimal import Decimal,ROUND_HALF_UP
    #tmp = Decimal(mid).quantize(Decimal('0'), rounding=ROUND_HALF_UP)
    from functools import lru_cache, reduce
    #@lru_cache(maxsize=None)
    from operator import add,sub,mul,xor,and_,or_,itemgetter
    INF = 10**18
    mod1 = 10**9+7
    mod2 = 998244353
    
    #DecimalならPython
    
    
    '''
    
    
    
    '''
    
    K = int(input())
    
    dp = [0]*(K+7)
    
    for i in reversed(range(K)):
        for j in range(1,7):
            dp[i] += (dp[i+j]+1)/6
    
    print(dp[0])
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
if __name__ == '__main__':
    main()