<?php

// your code goes here

$phone = fgets(STDIN);
$i = 1; $k = 0;
$new_phone = '';
for ($i = 0; $i <= strlen($phone)-1; $i++){
if (is_numeric(substr($phone, $i, 1))) {$new_phone .= substr($phone, $i, 1); $k++;}
if (($k > 2) && ($k % 3) == 0) {$new_phone .= '-'; $k = 0;}
}
fwrite(STDOUT, $new_phone);

?>