N=int(input())
dp=[[0 for i in range(7)] for j in range(N+1)]

dp[0][0]=1

for i in range(1,N+1):
    for j in range(1,7):
        dp[i][j]+=dp[i-1][j-1]*(7-j)/6
        dp[i][j]+=dp[i-1][j]*j/6
        
print(dp[N][6])