A[0]
C
D
####
A[0]
B
C
D[0]
D1
DA
####
#!/usr/local/bin/perl
use strict;
use warnings;
if (@ARGV != 3) {
print "Usage: $0 ##
Search pattern: ^(?:A\[0\]|C|D)[^a-zA-Z]*$
input : A[0]
input : B
output: B
input : C
input : D[0]
input : D1
input : DA
output: DA