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: Runtime Error)

private fun readLn() = readLine()!! // string line
private fun readInt() = readLn().toInt() // single int
private fun readStrings() = readLn().split(" ") // list of strings
private fun readInts() = readStrings().map { it.toInt() } // list of ints


fun mySqrt(x: Int): Int {
    var low: Long = 0
    var high = x.toLong()
    var mid = x.toLong()
    while (low <= high) {
        mid = low + (high - low) / 2
        if (mid * mid == x.toLong()) return mid.toInt() else if (mid * mid < x) low = mid + 1 else high = mid - 1
    }
    return if (mid * mid > x) mid.toInt() - 1 else mid.toInt()
}

fun isPrime(n: Int): Boolean {
    if (n > 2 && n % 2 == 0) return false
    var i = 3
    while (i <= mySqrt(n)) {
        if (n % i == 0) {
            return false
        }
        i += 2;
    }
    return n > 1
}

fun main() {

    var n = readInt()
    while (!isPrime(n)) {
        n++
    }
    println(n)

}