I am trying to write a formula so when a name is listed a number of times in column C the first column (A) adds by 1 (see below the QCD,QCD2..). I also need to include a condition where the attendance must match before counting up. For example below the column with O2 would not be QCD3 it would be the first instance of QCDOT.

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Screenshot refrs:

=A4&C4&SUM(1*(C$4:C4&D$4:D4=C4&D4))