find mismatch in 2 columns

dear friends,
in the attached xls, col 1 and 2 are the master code and description respectively. in cols 3 & 4, i have my list of codes and description. however, i think that in col 3 and 4, some of the codes do not match the description (as compared to the master). i would like a solution that identifies the rows where the code and description in col 3 and col 4 do not match the master. thanks for your help.

yours sincerely