#!/usr/bin/perl
use strict;
use warnings;

my $num = 0;
while ( my $line = <DATA> ) {
    if ( $num == 0 && $line =~ m/LESE (\d+)/ ) {
        $num = $1;
    }
    elsif ( $num > 0 ) {
        print $line;
        $num--;
    }

}

__DATA__
LESE 3
a1
a2
a3
LESE 2
b1
b2
LESE 2
c1
c2