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.*;
import static java.lang.Math.*;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		long x = sc.nextLong();
		
		// 計算
		long result = 0;
		if(x == 2) result = 2;
		while(result == 0){
		    boolean flg = true;
		    for(int i = 2; i <= sqrt(x); i++){
		        if(x%i == 0){
		            flg = false;
		            break;
		        }
		    }
		    if(flg) result = x;
		    x++;
		}
		
		
		
		// 出力
		System.out.println(result);
	}
}