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: Wrong Answer)

import java.util.*;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // get a string
        int a = sc.nextInt();
        if (a == 2) {
                System.out.printf("%d%n",a);
            }
        if (a % 2 == 0) a += 1;
        while (true) {
            if (isPrime(a)) {
                System.out.printf("%d%n",a);
                break;
            }
            a += 2;
        }
        
    }
    
    private static boolean isPrime(int a) {
        for (int b = 3; b * b <= a; b += 2) {
                if (a % b == 0) {
                    return false;
                }
            } 
        return true;
    }
}