void NFS(int max)
	{
		int inter,index,mqrt=(int)sqrt(max)+1;
		for(int beg=3; beg <= mqrt; beg+=2)
		{
			index = beg*beg;
			inter = beg<<1;
			while(index < max)
			{
				isprime[index] = true;
				index += inter;
			}
			while(isprime[beg+2] == true)
				beg += 2;
		}
	}