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);
    long X = sc.nextLong();
    sc.close();

    for (long i = X; i < 100007; i++) {
      if (isPrimeNumber(i)) {
        System.out.println(i);
        return;
      }
    }
  }

  private static boolean isPrimeNumber(long num) {
    if (1 >= num) return false;
    if (2 == num) return true;
    long n = (long) Math.sqrt(num);
    for (long i = 2; i <= n; ++i) {
      if (0 == (num % i)) return false;
    }
    return true;
  }
}