unix - How can I compare 3 files together (to see what is unique in one file)? -

i have 3 files file1.txt, file2.txt, file3.txt , of same format.

i want select records file1.txt not present in file2.txt, file3.txt based on col2, col3. please advise me how ?

i have checked post described on comparing 2 files common records , understood can done using awk.

thank you.

awk '(x=argind==3)&&!a[$2,$3];!x{a[$2,$3]++}' file{3,2,1}