Given an input string that represents a 'cell range' in a spreadsheet, return a list of all the cell names within the range. Output should be sorted by column ascending and then row ascending.

constraints

• input string need not be case sensitive. meaning, a1 is a valid cell like A1
• no constraints given on max rows or columns. columns like AA, AB,... are also in the scope
• row numbers start with 1.

Ex-1:
input string -> A1:B2
output -> {A1,A2,B1,B2}

Ex-2:
input string -> A-1:B2
output -> {}