Problem:
Score: 200 points

Problem Statement

The number 105 is quite special - it is odd but still it has eight divisors.
Now, your task is this: how many odd numbers with exactly eight positive divisors are there between 1 and N (inclusive)?

Constraints

N is an integer between 1 and 200 (inclusive).

Input

Input is given from Standard Input in the following format:

N

Output

Print the count.

Sample Input 1

105

Sample Output 1

1

Among the numbers between 1 and 105, the only number that is odd and has exactly eight divisors is 105.

Sample Input 2

7

Sample Output 2

0

1 has one divisor. 3, 5 and 7 are all prime and have two divisors. Thus, there is no number that satisfies the condition.

Solution in Ruby (2.7.1) (judge verdict: Accepted)

require 'prime'
n = gets.to_i
i = 1
ans = 0
while i*2 + 1 <= n
  count = 1
  Prime.prime_division(2*i+1).each do |factor|
    count *= factor[1] + 1
  end
  if count == 8
    ans += 1
  end
  i += 1
end
puts ans