#!/usr/bin/perl
use strict;

while ( <DATA> ) {
 chomp;
 my $line = $_;

 my $i = 0;
 foreach my $val ( split(',',$line) ) {
   if ( $i == 2 ) {
     $i = 0;
     print "$val\n";
     next;
   }
   print "$val,";
   $i ++;
 }
}

__DATA__
userid,application_id,time,userid,application_id,time,userid,application_id,time
,