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 Java (OpenJDK 11.0.6) (judge verdict: Accepted)

import java.util.*;
import java.math.*;

public class Main {
    void solve(){
        Scanner scan = new Scanner(System.in);
        String x = scan.next();
        BigInteger a = new BigInteger(x);
        System.out.println(a.nextProbablePrime().min(a.subtract(new BigInteger("1")).nextProbablePrime()));
    }
    
    public static void main(String[] args){
        new Main().solve();
    }
}