Problem:
Score : 600 points

Problem Statement

Given is a positive integer N.

We will choose an integer K between 2 and N (inclusive), then we will repeat the operation below until N becomes less than K.

Operation: if K divides N, replace N with N/K; otherwise, replace N with N-K.

In how many choices of K will N become 1 in the end?

Constraints

2 \leq N \leq 10^{12}

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the number of choices of K in which N becomes 1 in the end.

Sample Input 1

6

Sample Output 1

3

There are three choices of K in which N becomes 1 in the end: 2, 5, and 6.

In each of these choices, N will change as follows:

When K=2: 6 \to 3 \to 1

When K=5: 6 \to 1

When K=6: 6 \to 1

Sample Input 2

3141

Sample Output 2

13

Sample Input 3

314159265358

Sample Output 3

9

Solution in Rust (1.15.1) (judge verdict: Accepted)

fn read_stdin() -> String {
    use std::io::Read;
    let mut input = String::new();
    std::io::stdin().read_to_string(&mut input).unwrap();
    input
}

fn scan<'a, I: Iterator<Item = &'a str>, T: std::str::FromStr>(tokens: &mut I) -> T {
    tokens.next().unwrap().parse().ok().unwrap()
}

fn main() {
    let input = read_stdin();
    let tokens = &mut input.split_whitespace();
    let n: usize = scan(tokens);
    let mut ans: usize = 0;
    let mut k: usize = 2;
    while k * k <= n - 1 {
        if (n - 1) % k == 0 {
            ans += 1;
            if k * k < n - 1 {
                ans += 1;
            }
        }
        k += 1;
    }
    if n - 1 >= 2 {
        ans += 1;
    }
    let mut k: usize = 2;
    while k * k <= n {
        if n % k == 0 {
            let mut x = n;
            while x % k == 0 {
                x /= k;
            }
            if x % k == 1 {
                ans += 1;
            }
        }
        k += 1;
    }
    if n >= 2 {
        ans += 1;
    }
    println!("{}", ans);
}