Equal Sum v2

<?php
$array = explode(' ', readline());

for ($i = 0; $i < count($array); $i++) {
    $rightSum = array_sum(array_slice($array, $i + 1));
    $leftSum = array_sum(array_slice($array, 0, $i));
    if ($leftSum === $rightSum) {
        echo $i;
        return;
    }
}
echo count($array) === 1 ? 0 : 'no';