Function StringAddition(num1in,num2in)
   ' Cleanup
   num1 = Trim(num1in)
   num2 = Trim(num2in)

   if num1 = "" and num2 = "" then
      WScript.Quit
   elseif num1 = "" then
      StringAddition = num2
   elseif num2 = "" then
      StringAddition = num1
   end if

   if Asc(Mid(num1,Len(num1),1)) = 13 then
      num1 = Mid(num1,1,Len(num1)-1)
   end if
   if Asc(Mid(num2,Len(num2),1)) = 13 then
      num2 = Mid(num2,1,Len(num2)-1)
   end if
   if Asc(Mid(num1,Len(num1),1)) = 10 then
      num1 = Mid(num1,1,Len(num1)-1)
   end if
   if Asc(Mid(num2,Len(num2),1)) = 10 then
      num2 = Mid(num2,1,Len(num2)-1)
   end if
   if Asc(Mid(num1,Len(num1),1)) = 13 then
      num1 = Mid(num1,1,Len(num1)-1)
   end if
   if Asc(Mid(num2,Len(num2),1)) = 13 then
      num2 = Mid(num2,1,Len(num2)-1)
   end if
   
   if num1 = "" and num2 = "" then
      WScript.Quit
   elseif num1 = "" then
      StringAddition = num2
   elseif num2 = "" then
      StringAddition = num1
   end if
   
   'fix an errar
   if Len(num2) > len(num1) then
      num1 = "0" & num1
   end if
   if Len(num1) > len(num2) then
      num2 = "0" & num2
   end if


      j = 1
      p = Int(Right(num1,j))
      q = Int(Right(num2,j))
      result = p+q
      carry = Int(result) \ 10
      result = Int(Int(result) mod 10)
      if Carry <> 0 then
         num1 = StringAddition(Mid(num1,1,Len(num1)-1), carry) & result
      end if
      if Len(num1) > 1 Then
         StringAddition = TrimLeadingZeros(StringAddition(Mid(num1,1,Len(num1)-1),Mid(num2,1,Len(num2)-1)) & result)
      else 
         StringAddition = TrimLeadingZeros(carry & result)
      end if
End Function

Function StringSubtraction(num1in,num2in)
   ' Cleanup
   num1 = Trim(num1in)
   num2 = Trim(num2in)

   if num1 = "" and num2 = "" then
      WScript.Quit
   elseif num1 = "" then
      StringSubtraction = num2
      Exit Function
   elseif num2 = "" then
      StringSubtraction = num1
      Exit Function
   end if

   'the following fixes newlines in the input
   if Asc(Mid(num1,Len(num1),1)) = 13 then
      num1 = Mid(num1,1,Len(num1)-1)
   end if
   if Asc(Mid(num2,Len(num2),1)) = 13 then
      num2 = Mid(num2,1,Len(num2)-1)
   end if
   if Asc(Mid(num1,Len(num1),1)) = 10 then
      num1 = Mid(num1,1,Len(num1)-1)
   end if
   if Asc(Mid(num2,Len(num2),1)) = 10 then
      num2 = Mid(num2,1,Len(num2)-1)
   end if
   if Asc(Mid(num1,Len(num1),1)) = 13 then
      num1 = Mid(num1,1,Len(num1)-1)
   end if
   if Asc(Mid(num2,Len(num2),1)) = 13 then
      num2 = Mid(num2,1,Len(num2)-1)
   end if
   
   if num1 = "" and num2 = "" then
      WScript.Quit
   elseif num1 = "" then
      StringSubtraction = num2
      ExitFunction
   elseif num2 = "" then
      StringSubtraction = num1
      ExitFunction
   end if

   If Mid(num1,1,1) = "-" and Mid(num2,1,1) = "-" Then
      StringSubtraction = StringSubtraction(Mid(num2,2,Len(num2)-1),Mid(num1,2,Len(num1)-1))
      Exit Function
   ElseIf Mid(num1,1,1) = "-" Then
      StringSubtraction = "-" & StringAddition(num2,Mid(num1,2,Len(num1)-1))
      Exit Function
   Elseif Mid(num2,1,1) = "-" Then
      StringSubtraction = StringAddition(Mid(num2,2,Len(num2)-1),num1)
      Exit Function
   End If

   wib = WhichIsBigger(num1,num2)
   if wib = 2 then
      StringSubtraction = "-" & StringSubtraction(num2,num1)
      Exit Function
   end if
   
   'fix an errar
   if Len(num2) > len(num1) then
      num1 = "0" & num1
   end if
   if Len(num1) > len(num2) then
      num2 = "0" & num2
   end if




      j = 1
      p = Int(Right(num1,j))
      q = Int(Right(num2,j))
      result = p-q
      if (result < 0) then 'and (wib <> 2) then
         carry = 1
         result = result + 10
      end if
      result = Int(Int(result) mod 10)
      if Carry <> 0 then
         num1 = StringSubtraction(Mid(num1,1,Len(num1)-1), Abs(carry)) & Abs(result)
      end if


      if Len(num1) > 1 Then
         StringSubtraction = TrimLeadingZeros(StringSubtraction(Mid(num1,1,Len(num1)-1),Mid(num2,1,Len(num2)-1)) & Abs(result))
      else 
         StringSubtraction = TrimLeadingZeros(Abs(carry) & Abs(result))
      end if
End Function

' Works out which integer (stored as a string) is larger
' this is used because the large numbers we are using are not capable of being stored
' in conventional VBScript Data Types
Function WhichIsBigger(num1, num2)
   WhichIsBigger = 0
   if Len(num1) > Len(num2) then
      WhichIsBigger = 1
   elseif Len(num2) > Len(num1) then
      WhichIsBigger = 2
   else
      for i = 1 to Len(num1)
         if (Int ( Mid (num1, i, 1) ) > Int ( Mid (num2, i, 1) ) ) then
            WhichIsBigger = 1
            i = Len(num1)+1
         elseif (Int ( Mid (num2, i, 1) ) > Int ( Mid (num1, i, 1) ) ) then
            WhichIsBigger = 2
            i = Len(num1)+1
         end if
      next
   end if

End Function