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: Accepted)

object Main extends App {
  val sc = new java.util.Scanner(System.in)
  var n = sc.nextInt

  var ans = 0
  while (ans == 0) {
    if(isPrime2(n))ans = n
    n += 1
  }
  println(ans)

  def isPrime(x: Int): Boolean = {
    var result = true
    if(x > 1) {
      for(i <- 2 until x) {
        if(x % i == 0) {
          result = false
        }
      }
    }else {
      result = false
    }
    result
  }
  def isPrime2(x: Int): Boolean = {
    var result = true
    if(x > 1) {
      for(i <- 2 until math.sqrt(x).toInt) {
        if(x % i == 0) {
          result = false
        }
      }
    }else {
      result = false
    }
    result
  }
}