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 Rust (1.15.1) (judge verdict: Wrong Answer)


use std::io::*;
use std::str::FromStr;

pub fn read<T: FromStr>() -> T {
  let stdin = stdin();
  let stdin = stdin.lock();
  let token: String = stdin
    .bytes()
    .map(|c| c.expect("failed to read char") as char)
    .skip_while(|c| c.is_whitespace())
    .take_while(|c| !c.is_whitespace())
    .collect();
  token.parse().ok().expect("failed to parse token")
}

// use std::cmp::{max, min};

fn divisors(n: usize) -> Vec<usize> {
  let mut divisors = Vec::new();
  for i in 1..(f64::sqrt(n as f64) + 1e-9) as usize {
    if n % i == 0 {
      divisors.push(i);
      if i != n / i {
        divisors.push(n / i);
      }
    }
  }
  divisors.sort();
  divisors
}

fn main() {
  let n = read::<i32>();
  let mut count = 0;

  for i in 1..n + 1 {
    if i % 2 == 1 && divisors(i as usize).len() == 8 {
      count += 1;
    }
  }

  println!("{}", count);
}