import sys

sys.setrecursionlimit(10 ** 6)
int1 = lambda x: int(x) - 1
p2D = lambda x: print(*x, sep="\n")
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]

def main():
    n = int(input())
    dp = [[0] * (n + 1) for _ in range(n+1)]
    dp[0][0] = 1
    ans = 0
    for i in range(n):
        for j in range(n):
            pre=dp[i][j]/6
            for k in range(j+1,j+7):
                dp[i+1][min(k,n)]+=pre
        ans+=dp[i+1][n]*(i+1)
    print(ans)

main()