Merging Cells Contents Based On Unique Identifiers

I’m having some problems writing a macro,

I have a spreadsheet with 2 columns. The first column is the index number (unique identifier) of the second column’s data that will repeat itself as many rows as needed. Let me try to exemplify it:

Column A (index)Column B (text)
1 AAA
1 BBB
1 CCC
2 DDD
2 EEE
3 FFF
3 GGG
3 HHH
3 III

I’m trying to write a macro that will merge the text of each identifier in the first row it appears. The result I’m looking for is:

Column A (index)Column B (text)
1AAA
BBB
CCC
2DDD
EEE
3FFF
GGG
HHH
III

I already know how to make the merge, but I can’t get the logic to make it go through each row and merge the contents, since the number or rows for each identifier varies.