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 (1.42.0) (judge verdict: Accepted)

use text_io::*;
use std::process::exit;
use im_rc::HashMap;
use std::cmp::min;

fn main() {
    let mut n:usize = read!();
    let mut a:usize = 1;
    let mut b:usize = 0;
    for _ in 0..100000000 {
        for i in 2..(n as f64).sqrt() as usize+1 {
            if n%i==0 {
                b+=1;
            }
        }
        if b==0 && n!=1 {
            println!("{}",n);
            exit(0);
        }
        n+=1;
        b=0;
    }
}