import java.util.*;

import static java.lang.Math.*;


public class NaivePrimes {
    public static void main (String...args) {
        final int maxValue = args.length < 1 ? 1000000 : (int)Double.parseDouble(args[0]);
        final int maxSqrt = (int)ceil(sqrt(maxValue));

        System.out.println("Creating bit set");
        BitSet primeBits = new BitSet(maxValue);
        primeBits.set(0, maxValue, true);

        System.out.println("Sieving");
        /*
         * Sieve of Eratosthenes
         * primeBits is a simple BitSet where all bit is an integer
         * and we mark composite numbers as false
         */

        primeBits.set(0, false); // You don't actually need this, just
        primeBits.set(1, false); // remindig you that 2 is the smallest prime

        for (int p = 2; p < maxValue; p++) {
            if (primeBits.get(p)) {
                // These are going to be the multiples of P if it is a prime
                if (p < maxSqrt)
                    for (int pMultiply = p * p; pMultiply < maxValue; pMultiply += p)
                        primeBits.set(pMultiply, false);

                WheelPrimes.printPrime(p);
            }
        }

        System.out.println("found " + WheelPrimes.primeCount + " primes below " + maxValue + ".");
    }
}