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.*;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int X = sc.nextInt();
        sc.close();

        if (X == 2) {
            System.out.println(X);
            return;
        }
        int ans = X;
        for (int x = X; x < X * 2; x++) {
            if (x % 2 == 0) continue;
            int sqrt = (int) Math.sqrt(x);
            boolean s = false;
            for (int j = 3; !s && j <= sqrt; j += 2) {
                if (x % j == 0) s = true;
            }
            if (!s) {
                ans = x;
                break;
            }
        }

        System.out.println(ans);
    }
}