Prime

public class BitSetPrime {

    public static void main(String[] args) {
    BitSet p=new BitSet(2000000);
    p.flip(2,2000000); //Considering all numbers to be prime except 0 and 1
    for(int i=2 ;i<2000000;i++)
    {
        if(!p.get(i))
            continue;
        else
              // Set all multiples as not prime
              for(int j = 2*i; j < 2000000; j += i)
                 p.set(j,false);
    }
    long sum=0;
     for(int i = 2; i < 2000000; ++i)
            if( p.get(i) )  // Add all nos with bit set
              sum += i;
    System.out.println(sum);

}
}