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 Kotlin (1.0.0) (judge verdict: Accepted)

fun main(args: Array<String>) {
    var ans = nextLong()
    while (!isPrime(ans)) ans += 1
    println(ans)
}
fun next() = readLine()!!
fun nextLong() = next().toLong()
fun isPrime(n: Long): Boolean {
    if (n == 1L) return false
    for (k in 2 .. Math.sqrt(n.toDouble()).toLong()) {
        if (n % k == 0L) return false
    }
    return true
}