#!/usr/bin/perl
use strict;
my $flag  = 0;
my @lines = ();
while (<DATA>){
  if (/^\s*END/){
    $flag = 0
  } elsif (/^\s*START/){
    $flag = 1;
    @lines = ();
  } elsif ($flag) {
    push @lines,$_;
  }
}

print join '',@lines;