<?php
 $number = 'ё123жп';
 $regexp = '/[а-яё]{1}[0-9]{3}[а-яё]{2}/u';
 $matches = array();
 if(preg_match($regexp,$number,$matches)){
 	echo"Allright, move on\n ";
 }
 	else{
 		echo"Something wrong, lets try it again\n";
 	}
 
 var_dump($matches);

// your code goes here