<?php
/**
 * Correctness  :  100%
 * Performance  :  not assesed
 * Complexity   :  ?
 * Task score   :  100
 */
function solution($N) {
    $b = decbin($N); // converting to binary
    $b = trim($b, 0); // removing trailing zeros
    $bP = explode('1', $b); // dividing parts containing zeros
    $l = array_map('strlen', $bP); // array mapping
    return max($l); // returing max lengthed array element which is the longest gap
}

?>