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

my $begin_flag=0;
my $end_flag=0;
my $blank_line=0;
my $begin_count=0;

for my $i (1.. 3)
{
open(my $file1, '<', "input_$i.txt");   
open(my $file2, '>', "output_$i.txt");       

while(my $line= <$file1>) 
{ 
  $begin_flag =1 if($line =~ /^x/);
  $end_flag   =1 if($line =~ /^y/);
if($begin_flag==1 && $end_flag==0 && $begin_count++ >0)
    {
      print $file2 $line  if($line !~ /^\s*$/);   
    }
}
close $file1;
close $file2;
}