import java.io.*
import java.util.*

fun solve(X: Long){
    var x = X
    while(!isPrime(x)){
        x++
    }
    println(x)
    return
}

fun isPrime(num: Long): Boolean {
    if (num == 1L) return false
    if (num in listOf(2L, 3L)) return true
    if (num % 6 in listOf(0L, 2L, 3L, 4L)) return false
    val sqrt = Math.sqrt(num.toDouble()).toLong()
    for (n in 5..sqrt step 6) {
        if (num % n == 0L) return false
    }
    for (n in 7..sqrt step 6) {
        if (num % n == 0L) return false
    }
    return true
}


fun main(args: Array<String>) {
    fun StringArray(size: Int, init: (Int) -> String = { "\u0000" }): Array<String> {
        return Array<String>(size, init)
    }
    class Scanner(stream: InputStream) {
        private val reader = BufferedInputStream(stream).bufferedReader()
        private var st: StringTokenizer? = null
        fun next(): String {
            while (!(st?.hasMoreTokens() ?: false)) st = StringTokenizer(reader.readLine())
            return st!!.nextToken()
        }
    }
    val sc = Scanner(System.`in`)
    val X = sc.next().toLong()
    solve(X)
}

