#! /usr/bin/perl

use warnings;
use strict;
# Skip 6 lines at beginning of file
# Throw away 3 lines before \f
# Skip 5 lines after \f
use constant LINES_TO_SKIP_AT_START => 6;
use constant LINES_TO_SKIP_BEFORE_FF => 4;
use constant LINES_TO_SKIP_AFTER_FF => 3;
our @lines;
our $lines_to_skip = 6;
LINE: while ( <> ) {
    if ( $lines_to_skip ) {
        --$lines_to_skip;
        next LINE;
    }
    if ( /\f/ ) {
        $#lines -= LINES_TO_SKIP_BEFORE_FF;
        $lines_to_skip = LINES_TO_SKIP_AFTER_FF;
        next;
    }
    push @lines, $_;
    print shift @lines if @lines > LINES_TO_SKIP_BEFORE_FF;
}
# Get rid of the last few lines if they are blank:
for ( my $i = $#lines; $i >= 0; --$i) {
    last if $lines[ $i ] =~ /\S/;
    --$#lines;
}
print @lines;