Problem:
Score : 400 points

Problem Statement

Given are positive integers A and B.

Let us choose some number of positive common divisors of A and B.

Here, any two of the chosen divisors must be coprime.

At most, how many divisors can we choose?

Definition of common divisor

An integer d is said to be a common divisor of integers x and y when d divides both x and y.

Definition of being coprime

Integers x and y are said to be coprime when x and y have no positive common divisors other than 1.

Definition of dividing

An integer x is said to divide another integer y when there exists an integer \alpha such that y = \alpha x.

Constraints

All values in input are integers.

1 \leq A, B \leq 10^{12}

Input

Input is given from Standard Input in the following format:

A B

Output

Print the maximum number of divisors that can be chosen to satisfy the condition.

Sample Input 1

12 18

Sample Output 1

3

12 and 18 have the following positive common divisors: 1, 2, 3, and 6.

1 and 2 are coprime, 2 and 3 are coprime, and 3 and 1 are coprime, so we can choose 1, 2, and 3, which achieve the maximum result.

Sample Input 2

420 660

Sample Output 2

4

Sample Input 3

1 2019

Sample Output 3

1

1 and 2019 have no positive common divisors other than 1.

Solution in Rust (1.15.1) (judge verdict: Wrong Answer)

//  ____            _                  _                       _       _
// |  _ \ _   _ ___| |_    ___ _ __   | |_ ___ _ __ ___  _ __ | | __ _| |_ ___
// | |_) | | | / __| __|  / __| '_ \  | __/ _ \ '_ ` _ \| '_ \| |/ _` | __/ _ \
// |  _ <| |_| \__ \ |_  | (__| |_) | | ||  __/ | | | | | |_) | | (_| | ||  __/
// |_| \_\\__,_|___/\__|  \___| .__/___\__\___|_| |_| |_| .__/|_|\__,_|\__\___|
//                            |_| |_____|               |_|

//                                                     _        _ _ _____  ___
//                               _ __ ___   __ _ _ __ | |_ __ _/ / |___ / / _ \
//                              | '_ ` _ \ / _` | '_ \| __/ _` | | | |_ \| | | |
//                              | | | | | | (_| | | | | || (_| | | |___) | |_| |
//                              |_| |_| |_|\__,_|_| |_|\__\__,_|_|_|____/ \___/

//https://github.com/manta1130/Competitive_Programming_Template_Rust

#[macro_use]
mod input {

    use std;
    use std::io;

    const SPLIT_DELIMITER: char = ' ';

    #[macro_export]
    #[allow(unused_macros)]
    macro_rules! input {
    ( $($x:expr ),*) => {
        {
            let temp_str = input_line_str();
            let mut split_result_iter = temp_str.split_whitespace();
                $(
                let buf_split_result = split_result_iter.next();
                let buf_split_result = buf_split_result.unwrap();
                    ($x) = buf_split_result.parse().unwrap();
                )*
        }
    };
}

    #[allow(dead_code)]
    pub fn input_line_str() -> String {
        let mut s = String::new();
        io::stdin().read_line(&mut s).unwrap();
        s.trim().to_string()
    }

    #[allow(dead_code)]
    pub fn p<T>(t: T)
    where
        T: std::fmt::Display,
    {
        println!("{}", t);
    }

    #[allow(dead_code)]
    pub fn input_vector2d<T>(line: usize) -> Vec<Vec<T>>
    where
        T: std::str::FromStr,
    {
        let mut v: Vec<Vec<T>> = Vec::new();

        for _ in 0..line {
            let vec_line = input_vector();
            v.push(vec_line);
        }
        v
    }

    #[allow(dead_code)]
    pub fn input_vector<T>() -> Vec<T>
    where
        T: std::str::FromStr,
    {
        let mut v: Vec<T> = Vec::new();

        let s = input_line_str();
        let split_result = s.split(SPLIT_DELIMITER);
        for z in split_result {
            let buf = match z.parse() {
                Ok(r) => r,
                Err(_) => panic!("Parse Error"),
            };
            v.push(buf);
        }
        v
    }

    #[allow(dead_code)]
    pub fn input_vector_row<T>(n: usize) -> Vec<T>
    where
        T: std::str::FromStr,
    {
        let mut v = Vec::with_capacity(n);
        for _ in 0..n {
            let buf = match input_line_str().parse() {
                Ok(r) => r,
                Err(_) => panic!("Parse Error"),
            };
            v.push(buf);
        }
        v
    }

    pub trait ToCharVec {
        fn to_charvec(&self) -> Vec<char>;
    }

    impl ToCharVec for String {
        fn to_charvec(&self) -> Vec<char> {
            self.to_string().chars().collect::<Vec<_>>()
        }
    }
}

#[macro_use]
mod prime_number {

use std::iter::Iterator;

pub struct PrimeFactorization {
    n: usize,
    cur: usize,
    limit: usize,
}

///素因数分解
impl PrimeFactorization {
    ///素因数を計算するイテレータを返す。
    pub fn calc(n: usize) -> PrimeFactorization {
        PrimeFactorization {
            n: n,
            cur: 1,
            limit: (n as f64).sqrt() as usize + 1,
        }
    }
}

impl Iterator for PrimeFactorization {
    type Item = usize;
    fn next(&mut self) -> Option<Self::Item> {
        loop {
            if self.cur == 0 || self.cur > self.n {
                return None;
            }

            self.cur += 1;

            if self.cur > self.limit {
                if self.n != 1 {
                    self.cur = 0;
                    return Some(self.n);
                }
                return None;
            }
            if self.n % self.cur == 0 {
                self.n /= self.cur;
                self.cur -= 1;
                return Some(self.cur + 1);
            }
        }
    }
}
}

use input::*;
use prime_number::*;
use std::collections::{HashMap, HashSet};

fn dfs(
    table: &Vec<HashSet<usize>>,
    v: HashSet<usize>,
    i: usize,
    c: usize,
    memo: &mut Vec<Vec<usize>>,
) -> usize {
    if memo[i][c] != 999999999999 {
        return memo[i][c];
    }

    if i >= table.len() {
        return c;
    }

    let p1 = dfs(table, v.clone(), i + 1, c, memo);
    memo[i + 1][c] = p1;
    let buf = &v & &table[i];
    let mut p2 = 0;
    if buf.len() == 0 {
        memo[i + 1][c + 1] = dfs(table, &v | &table[i], i + 1, c + 1, memo);
        p2 = memo[i + 1][c + 1];
    }
    std::cmp::max(p1, p2)
}

fn main() {
    let (a, b): (usize, usize);
    input!(a, b);

    let mut v = vec![0_usize];
    v.clear();

    for z in 1..((std::cmp::max(a, b) as f64).sqrt()) as usize + 10000 {
        if a % z == 0 && b % z == 0 {
            v.push(z);
        }
    }
    if a == b && *v.last().unwrap()!=a {
        v.push(a);
    }
    v.sort();

    let mut ans = HashSet::new();

    let mut table = vec![];

    for z in v {
        let s = PrimeFactorization::calc(z).collect::<HashSet<_>>();
        table.push(s);
    }
    let mut memo = vec![vec![999999999999; table.len() + 1]; table.len() + 1];
    println!("{}", dfs(&table, ans, 0, 0, &mut memo));
}