Rownumber in table in CSV-format


I compare two CSV-tables in a robot, an OutputTable 1 vs StandardTable 2. My robot checks if table 2 complies with the values of table 1.

Since the format in table 1 may not be changed, I would like to use a write line which gives me the rownumber or rownumbers of the rows which does not comply with the condition.

Who knows what I can use - in for instance a messagebox - what gives me the rownumber / rownumbers, if it is not in line with my condition?

Best, Matt