UNIX for Dummies Questions & Answers

I have an array containing bunch of characters. I have to check this array for specific character and if "Not Found than" use a goto statement to go to USAGE

Code:

set options = (A B C D E F)
@ i = 0
while ($i <= ${#options})
  if ($options[$i] != "F" || $options[$i] != "D") then
  goto USAGE
 endif
@ i++
end

In above code I am looking for F and D and if not found than script goes to USAGE defined somewhere in script. I know it can be done with awk/sed/grep as one liner which I think more efficient. I am new to this and want to move away from doing things in an ancient way. Please help.
Thanks in advance

Code:

 
$ echo "A B C D E F" | nawk '!/D/ && !/F/ {print "USAGE :: "}'
$
$ echo "A B C E " | nawk '!/D/ && !/F/ {print "USAGE :: "}'
USAGE ::