class Exercise4
{
  // returns true if "x" occurs among the first "n" elements of "a"
  public static boolean has(int[] a, int n, int x) 
  {
    boolean r = false;
    for (int i = 0; i < n && !r; i++) 
    {
      if (a[i] == x) r = true;
    }
    return r;
  }
  
  // compacts array "a" to a "set" that does not contain duplicate elements;
  // the distinct elements are moved to the initial portion of "a" and
  // their number is returned as a result.
  public static int toset(int[] a) 
  {
    int n = a.length;
    int ia = 0;
    int ib = 0;
    while (ia < n)
    {
      boolean has = has(a,ib,a[ia]);
      if (!has)
      {
        a[ib] = a[ia];
        ib = ib+1;
      }
      ia = ia+1;    
    }
    return ib;
  }
}