Add incremental, non consecutive, unique ID for non blank rows

Example table has 2 columns and 10 rows. First column consists of names manually entered. I need to produce unique id in second column in order data are entered in columns. When I enter name in A3, B3 should be 1, if the next name is entered in A6, then B6 is 2, next entered name is in A1, and B1 is 3.
Is there a way this can be done? My actual table have several hundreds of rows so its hard to keep track manually.

It would be a lot simpler if you just added new data to the bottom of a contiguous set of data.

Pete

Yes it would, but real life problems are never simple. I would have to sort previous entries (which isnt easy because there are lot of merged cells preventing simlpe sorting), find the latest entry (biggest number) and then enter the value in target cell and incremented number in a column screen and a half to the right (my table have more than 50 columns). Its doable but not easy. Thats why I need help making it easier. Maybe a macro would do it, but im not familiar with macros.