#define  NMAX    65536
#define  MAXBITS    32

void isqrt(unsigned int x, unsigned int *outp)
{
  unsigned int m, y, b, a;
  
  a = x;
  m = 0x1 << (MAXBITS-2);
  y = 0;
  
  while (m != 0)
  {
    b = y | m; 
    y = y >> 1; 
    
    if (a >= b) 
    {
      a = a - b; 
      y = y | m; 
    } 
    m = m >> 2; 
  } 
  
  *outp = y;
}

void sieve(unsigned int n, unsigned int *outp)
{
  static unsigned int erat[NMAX];
  unsigned int count, m, i, j, x;	
  x = n;
  for (i = 0; i < NMAX; i++)
  {
    erat[i] = 0;
  }
  count = 0;
  erat[0] = 1;
  erat[1] = 1;
  isqrt(x, &m);
  for (i = 2; i <= m; i++) 
  {
    if (erat[i] == 0) 
    {
      for (j = i*i; j <= x; j += i) 
      {
        erat[j] = 1;
      }
    }
  }
  
  for (i = 2; i <= x; i++)
  {
    if (erat[i] == 0)
    {
      count++;
	}
  }
  *outp = count;
}