Problem:
Score : 400 points

Problem Statement

Given is a positive integer N. Consider repeatedly applying the operation below on N:

First, choose a positive integer z satisfying all of the conditions below:

z can be represented as z=p^e, where p is a prime number and e is a positive integer;

z divides N;

z is different from all integers chosen in previous operations.

Then, replace N with N/z.

Find the maximum number of times the operation can be applied.

Constraints

All values in input are integers.

1 \leq N \leq 10^{12}

Input

Input is given from Standard Input in the following format:

N

Output

Print the maximum number of times the operation can be applied.

Sample Input 1

24

Sample Output 1

3

We can apply the operation three times by, for example, making the following choices:

Choose z=2 (=2^1). (Now we have N=12.)

Choose z=3 (=3^1). (Now we have N=4.)

Choose z=4 (=2^2). (Now we have N=1.)

Sample Input 2

1

Sample Output 2

0

We cannot apply the operation at all.

Sample Input 3

64

Sample Output 3

3

We can apply the operation three times by, for example, making the following choices:

Choose z=2 (=2^1). (Now we have N=32.)

Choose z=4 (=2^2). (Now we have N=8.)

Choose z=8 (=2^3). (Now we have N=1.)

Sample Input 4

1000000007

Sample Output 4

1

We can apply the operation once by, for example, making the following choice:

z=1000000007 (=1000000007^1). (Now we have N=1.)

Sample Input 5

997764507000

Sample Output 5

7

Solution in Rust (1.42.0) (judge verdict: Accepted)

use std::collections::HashMap;
use std::f64;

#[allow(unused)]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}
#[allow(unused)]
macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};

    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}
#[allow(unused)]
macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}
#[allow(unused)]
fn round_to_integer(a: f64, digit: u8) -> i64 {
    let mut ai: i64;
    let mut d = digit;
    let mut p = 1;

    while d > 0 {
        p *= 10;
        d -= 1;
    }
    ai = (a * p as f64) as i64;

    while ai as f64 / p as f64 - a > 0.5 / p as f64 {
        ai -= 1;
    }
    while ai as f64 / p as f64 - a < -0.5 / p as f64 {
        ai += 1;
    }
    ai
}
fn trial_division(mut n: usize) -> HashMap<usize, usize> {
    let mut primes = HashMap::new();
    let mut i = 2;

    //  n を root n 以下の整数で割り切れるまで割っていく
    while i * i <= n {
        while n % i == 0 {
            n /= i;
            if primes.contains_key(&i) {
                let x = primes.get_mut(&i).unwrap();
                *x += 1;
            } else {
                primes.insert(i, 1);
            }
        }
        i += 1;
    }

    // 最後にnが素数になっている場合はそれ自身も素因数に含めて終了
    if n > 1 {
        if primes.contains_key(&n) {
            let x = primes.get_mut(&n).unwrap();
            *x += 1;
        } else {
            primes.insert(n, 1);
        }
    }
    primes
}

fn main() {
    input! {
        n : usize,
    }
    let x = trial_division(n);
    let mut counter = 0;
    for map in x.iter() {
        let mut n = *(map.1);

        let mut coll: Vec<u64> = Vec::new();

        let mut sub: u64 = 1;
        while n >= sub as usize {
            if !coll.contains(&sub) {
                coll.push(sub);
                n -= sub as usize;
                sub += 1;
            } else {
                break;
            }
        }
        counter += coll.len();
    }
    println!("{}", counter);
}