A format for expressing an ordered list of integers is to use a comma separated list of either

 individual integers
 Or a range of integers denoted by the starting integer separated from the end integer in the range by a dash, '-'. (The range includes all integers in the interval including both endpoints)
 The range syntax is to be used only for, and for every range that expands to more than two values.
Example

The list of integers:

 -6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20
Is accurately expressed by the range expression:

 -6,-3-1,3-5,7-11,14,15,17-20
(And vice-versa).



Task

Expand the range description:

  -6,-3--1,3-5,7-11,14,15,17-20 

Note that the second element above,
is the range from minus 3 to minus 1. 



Related task

   Range extraction


print ExpandRange$( "-6,-3--1,3-5,7-11,14,15,17-20")
end
 
function ExpandRange$( compressed$)
    for i = 1 to ItemCount( compressed$, ",")
        item$ = word$( compressed$, i, ",")
        dash  = instr( item$, "-", 2) 'dash that is not the first character, is a separator
        if dash then
            for k = val( left$( item$, dash - 1)) to val( mid$( item$, dash + 1))
                ExpandRange$ = ExpandRange$ + str$( k) + ","
            next k
        else
            ExpandRange$ = ExpandRange$ + item$ + ","
        end if
    next i
    ExpandRange$ = left$( ExpandRange$, len( ExpandRange$) - 1)
end function
 
function ItemCount( list$, separator$)
    while word$(list$, ItemCount + 1, separator$) <> ""
        ItemCount = ItemCount + 1
    wend
end function