Php_merge_array

<?php

$arFirst = array('mama', 'papa', 'horse');
$arSecond = array('class', 'grandma', 'keyboard');

$pairArray = array();
$notPair = array();

$test = implode(" " , $arFirst);
$testTwo = implode(" " , $arSecond);

function count_letter($x) {
    $count = 0;
    for ($i = 0; $i < strlen($x); $i++) {
        if (strpos('euoaiy', $x[$i]) > -1) {
            $count++;
        }
    }
    return $count;
}



if(count_letter($test) % 2 ===0) {
    array_unshift($pairArray , $test);

}else {
    array_unshift($notPair , $test);

}

if(count_letter($testTwo) % 2 ===0) {
     array_unshift($pairArray , $testTwo);

}else {
    array_unshift($notPair , $testTwo);

}

$res = array_merge($pairArray,$notPair);
print_r($res);





?>