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 Scala (2.11.7) (judge verdict: Wrong Answer)

object Main {
  def main(args:Array[String]) {
    val X = readLine().toInt
    val max = 100003
    var num = List.range(2, 100004)
    var prime = List[Int]()

    var n = num(0)
    while(n <= math.sqrt(max)) {
      prime = prime :+ n
      num = num.filter(_ % n != 0)
      n = num(0)
    }
    prime  = prime ::: num
    var ans = 0
    ans = prime.filter(_ > X)(0)
    println(ans)
  }
}