/**
 * Returns of max profit for the given market values
 * it there are not possible to compleat the deal it will return 0
 *
 * @param $marketValues the array wit market values, should contain at least one value
 * @return int
 */
function getMaxProfit($marketValues) : int
{
    $minValue = $marketValues[array_keys($marketValues)[0]];
    $maxProfit = 0;

    foreach($marketValues as $day => $value) {
        if ($minValue > $value) {
            $minValue = $value;
        }
        else if ($value - $minValue > $maxProfit) {
            $maxProfit = $value - $minValue;
        }
    }
    return $maxProfit;
}