<?php

error_reporting(-1);
mb_internal_encoding('UTF-8');

$text = "А роза упала на лапу Азора";
$result = "палиндром";

$text = mb_strtolower($text);
$length = mb_strlen($text);
$textWithoutSpaces = "";

for ($i = 0; $i < $length; ++$i) {
	$char = mb_substr($text, $i, 1);
	if ($char != ' ') {
		$textWithoutSpaces .= $char;		
	}	
}

$length = mb_strlen($textWithoutSpaces);
$halfLength = floor($length/2);

for ($i = 0; $i < $halfLength; ++$i) {
	$charOne = mb_substr($textWithoutSpaces, $i, 1);
	$charTwo = mb_substr($textWithoutSpaces, -($i + 1), 1);
	
	if ($charOne != $charTwo) {
		$result = "это не палиндром";
		break;
	}
}

echo $result;