table = []
[2,3,5,7,11,13].each{|a|
 [4,6,8,9,10,12].each{|b|
  table.push(a * b)
 }
}
hash = Hash.new(0)
table.each{|c|
 hash[c] += 1
}
print 1.0 * Rational(hash[gets.to_i],36)