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 proconio::{fastout, input};

#[fastout]
fn main() {
    input! {x: usize};

    if x == 2 || x == 3 {
        println!("{}", x)
    } else {
        for i in x..10000000000 {
            let mut k = true;
            let mut j = 3;
            while j <= (i as f64).sqrt() as usize + 2 {
                if i % j == 0 || i % 2 == 0 {
                    k = false;
                    break;
                }
                j += 2;
            }
            if k {
                println!("{}", i);
                break;
            }
        }
    }
}