#yuki_567
import sys

n=int(raw_input())
if n>100:
 print 1.0
 sys.exit()
dp=[[0 for i in xrange(7)] for j in xrange(n+1)]
dp[0][0]=1.0
for i in xrange(n):
 for j in xrange(7):
  dp[i+1][j]+=dp[i][j]*j/6.0
  if j<6:
   dp[i+1][j+1]+=dp[i][j]*(6.0-j)/6.0
print dp[n][6]