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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        
        //与えられた数が素数か素数でないかを見分けるには，2からN−1までの整数で割り切れるかどうか
        for (int n=x; ; n++) {
            if (judgeNumber(n)) {
                System.out.println(n);
                break;
            }
        }
    }
    
    private static boolean judgeNumber(int n) {
        for (int i=2; i<=n-1; i++) {
            if (n%i == 0){
                return false;
            }
        }
        return true;
    }
}