<?php

// your code goes here

$text = "+7(919)-122-88-99";
$result = null;

$userInputRegexp = '/^(8|[+]7)[\\(\\)0-9-]{10,40}/u';
$filterRegexp = '/[\\(\\)-]/u';
$changeFirstNumberRegexp = '/[+]7/u';

if (preg_match($userInputRegexp,$text)){
	$result = preg_replace($filterRegexp,"",preg_replace($changeFirstNumberRegexp,"8",$text));	
	echo $result;
} else
	echo "Wrong number!";