I'm trying to solve this problem https://www.codewars.com/kata/563b662a59afc2b5120000c6/train/php
in php and I arrived at a solution that passes the tests but at the time of sending it as an answer it does not accept:

function nbYear($p0, $percent, $aug, $p) {
$year = 0;
do{
$upYear = ($p0 * ($percent/100)) + $aug;
$p0 = $p0 + $upYear;
$year++;
}
while($p0 <= $p);
return $year;
}

I do not understand