import scala.io.StdIn.readInt
import scala.collection.mutable.ArrayBuffer

object Main {
  def sieve(n:Int) = {
    val list = Array.tabulate(n+1) { _ % 2 }
    val primes = new ArrayBuffer[Int]
    list(1) = 0
    list(2) = 2
    primes += 2

    for( i <- 3 to Math.sqrt(n).toInt by 2 )
    {
      if(list(i) == 1) {
        (i*i to n by i*2).foreach { list(_) = 0 }
        primes += primes(primes.length-1)+i
      }
    }
    for(i<-Math.sqrt(n).toInt+1 to n if list(i)==1)
      primes += primes(primes.length-1)+i
    primes.toArray
  }

  def main(args:Array[String]) = {
    val p = sieve(150000)
    var n = 0
    while( { n = readInt; n} != 0 ) println(p(n-1))
  }
}