class IntSet7
{
// Constructive Set class, implemented using arrays of integers

 private int[] array;

 public IntSet7()
 {
  array = new int[0];
 }

 private IntSet7(int[] a)
 {
  array = a;
 }

 public IntSet7 delete(int n)
 {
  int i;
  for(i=0; i<array.length&&array[i]<n; i++) {}
  if(i<array.length&&array[i]==n)
     {
      int[] array1 = new int[array.length-1];
      for(int j=0; j<i; j++)
         array1[j]=array[j];
      for(i++;i<array.length; i++)
         array1[i-1]=array[i];
      return new IntSet7(array1);
     }
  return this;
 }

 public IntSet7 add(int n)
 {
  int i;
  for(i=0; i<array.length&&array[i]<n; i++) {}
  if(i==array.length||array[i]>n)
     {
      int[] array1 = new int[array.length+1];
      for(int j=0; j<i; j++)
         array1[j]=array[j];
      array1[i]=n;
      for(int j=array.length; j>i; j--)
         array1[j]=array[j-1];
      return new IntSet7(array1);
     }
  return this;
 }

 public boolean member(int n)
 {
  int from=0, to=array.length;
  int mid=(from+to)/2;
  while(from!=to&&array[mid]!=n)
     {
      if(array[mid]>n)
         to=mid;
      else
         from=mid+1;
      mid=(from+to)/2;
     }
  return from!=to;
 }

 public String toString()
 {
  int i;
  String str="{";
  if(array.length>0)
     {
      str+=array[0];
      for(i=1;i<array.length;i++)
         str+=","+array[i];
     }
  return str+"}";
 }
}