Problem:
Score: 300 points

Problem Statement

Find the minimum prime number greater than or equal to X.

Notes

A prime number is an integer greater than 1 that cannot be evenly divided by any positive integer except 1 and itself.

For example, 2, 3, and 5 are prime numbers, while 4 and 6 are not.

Constraints

2 \le X \le 10^5

All values in input are integers.

Input

Input is given from Standard Input in the following format:

X

Output

Print the minimum prime number greater than or equal to X.

Sample Input 1

20

Sample Output 1

23

The minimum prime number greater than or equal to 20 is 23.

Sample Input 2

2

Sample Output 2

2

X itself can be a prime number.

Sample Input 3

99992

Sample Output 3

100003

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

#[allow(unused_imports)]
use std::io::*;

fn main() {
    let mut buff = String::new();
    stdin().read_line(&mut buff).unwrap();
    let mut itr = buff.split_whitespace();
    let mut x: i32 = itr.next().unwrap().parse().unwrap();


    let res: i32;
    loop {
        let mut i: i32 = (x as f64).sqrt().ceil() as i32;
        while i > 1 {
            if x != i && x % i == 0 {
                break;
            }
            i -= 1;
        }
        if i == 1 {
            res = x;
            break;
        }
        x += 1;
    }


    let out = stdout();
    let mut out = BufWriter::new(out.lock());
    let ans = format!("{}", res);
    writeln!(out, "{}", ans).unwrap();
}