Hi
This is probably very simple for someone on this forum but I could really use some help. I have the below three columns of data and i want to sum the NOM column everytime the same data appears in Col A and Col B... i assume i need some sort of running counter

For example 120000 and kadnoina appear together twice below so i want to return the sum of NOM from each time they appear together = 205

SKAC SEC NOM
120000 kadnoina 100
120001 adsclka 101
120002 akjnaiu 102
120003 ac5 103
120000 afasdf5 104
120000 kadnoina 105
120004 ac5 106
120005 asdsgfg 107
120006 afasdf5 108
120007 afasdf5 109
120007 afasdf5 110

Any help you can give would be GREATLY appreciated!!
Thanks