#coding: utf-8
##yuki_211

k=int(raw_input())

sp=[2,3,5,7,11,13]
sn=[4,6,8,9,10,12]
sm=[]

for i in xrange(6):
 for j in xrange(6):
  sm.append(sp[i]*sn[j])

sm.sort()

if k in sm:
 if k==12 or k==18 or k==20 or k==24 or k==30:
  print 2.0/36
 else:
  print 1.0/36
else:
 print "%.13f" % 0.0