using System; // Create a RangeArray exception. 

class RangeArrayException : Exception 

{ 

      public RangeArrayException() : base() 

      { 

      }  

      public RangeArrayException(string message) : base(message) 

      { 

      }  

      public RangeArrayException(string message, Exception innerException) : base(message, innerException) 

      { 

      }  

      protected RangeArrayException(System.Runtime.Serialization.SerializationInfo info,System.Runtime.Serialization.StreamingContext context) : base(info, context) 

      { 

      }   

      public override string ToString() 

      {    

      return Message;  

      } 

      }  

      class RangeArray {   

      int[] a;  

      int lowerBound;  

      int upperBound; 

      public int Length 

      { 

      get; 

      private set; 

      }

       public RangeArray(int low, int high) 

       {    

       high++;    

       if(high <= low) 

       {     

       throw new RangeArrayException("Low index not less than high.");   

       }    

       a = new int[high - low];    

       Length = high - low;    

       lowerBound = low;    

       upperBound = --high;  

       }  

       public int this[int index] 

       {        

       get 

       {     

       if(ok(index)) 

       {        

       return a[index - lowerBound];      

       } 

       else 

       {       

       throw new RangeArrayException("Range Error.");      

       }    

       }      

       set 

       {      

       if(ok(index)) 

       {        

       a[index - lowerBound] = value;      

       }     

       else throw new RangeArrayException("Range Error.");    

       }  

       } 

       private bool ok(int index) 

       {    

       if(index >= lowerBound & index <= upperBound) 

       return true;    

       return false;  

       } 

       }

       public class RangeArrayDemo 

       {  

           public static void Main() 

           {    

               try 

               {      

                   RangeArray ra = new RangeArray(-5, 5);      

                   RangeArray ra2 = new RangeArray(1, 10);         

                   Console.WriteLine("Length of ra: " + ra.Length);      

                   for(int i = -5; i <= 5; i++)        

                       ra[i] = i;

                     Console.Write("Contents of ra: ");      

                   for(int i = -5; i <= 5; i++)        

                       Console.Write(ra[i] + " ");      

                   Console.WriteLine("\n");          

                   Console.WriteLine("Length of ra2: " + ra2.Length);     

                   for(int i = 1; i <= 10; i++)        

                       ra2[i] = i;      

                   Console.Write("Contents of ra2: ");      

                   for(int i = 1; i <= 10; i++)        

                       Console.Write(ra2[i] + " ");      

                   Console.WriteLine("\n");   

               } 

               catch (RangeArrayException exc) 

               {      

                   Console.WriteLine(exc);    

               }    // Now, demonstrate some errors.    

               Console.WriteLine("Now generate some range errors.");  

               try 

               {      

                   RangeArray ra3 = new RangeArray(100, -10);    

               } 

               catch (RangeArrayException exc) 

               {      

                   Console.WriteLine(exc);    

               }    

               try 

               {      

                   RangeArray ra3 = new RangeArray(-2, 2);      

                   for(int i = -2; i <= 2; i++)        

                       ra3[i] = i;      

                   Console.Write("Contents of ra3: ");      

                   for(int i = -2; i <= 10; i++)        

                       Console.Write(ra3[i] + " ");    

               } 

               catch (RangeArrayException exc) 

               {       

                   Console.WriteLine(exc);    

               }  

           } 

       }