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 (2.3.3) (judge verdict: Accepted)

# https://atcoder.jp/contests/abc106/tasks/abc106_b

def divisors(n)
  ret = 0;
  1.upto(n) do |i|
    break if i * i > n
    if n % i == 0
      ret += 1
      ret += 1 if i != n / i
    end
  end
  ret
end

N = gets.to_i
vs = (1..N).select(&:odd?).select { |i| divisors(i) == 8 }

puts vs.size