https://www.hackerrank.com/challenges/time-conversion/problem

date_time_conversion.php

<?php

$handle = fopen ("php://stdin", "r");
function timeConversion($s) {
    // Complete this function
    $dateTime = DateTime::createFromFormat('h:i:sa', $s);
    
    return $dateTime->format('H:i:s');
}

fscanf($handle, "%s",$s);
$result = timeConversion($s);
echo $result . "\n";