#!/usr/bin/perl -w
use strict;

my $string= "ABCDEFGHIJKLMNOPCDEFQRST";
my $find="CDEF";

#extract first and last character
my ($first, $last) = $find =~ /([A-Z])[A-Z]*([A-Z])/;

#check both character present in string
if ($string =~ /$first/ && $string =~ /$last/) {
        
        print "'$find' string found" if ($string =~ /$find/);
}