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 scanner = new Scanner(System.in);
		int x = scanner.nextInt();
		scanner.close();
		if (x == 2) {
			System.out.println(2);
			return;
		}
		if (x % 2 == 0)
			x++;
		boolean isPrime;
		while (true) {
			isPrime = true;
			for (int i = 3; i * i <= x; i += 2) {
				if (x % i == 0) {
					isPrime = false;
					break;
				}
			}
			if (isPrime) {
				System.out.println(x);
				return;
			}
			x += 2;
		}
	}

}