Sort the output of the command "find . -type f" (which finds all files in the current directory and its subdirectories), converting all uppercase letters to lowercase and cutting the output at the third field, and count the number of occurrences of each unique result, sorting the output in descending order.
sort <(find . -type f  | tr '[:upper:]' '[:lower:]' | cut -d -f 3) | uniq -i -c | sort -nr