class Solution {
/**
* @param String $s
* @param String $t
* @return String
*/
function findTheDifference($s, $t) {
$targets = str_split($t);
$strings = str_split($s);
foreach($targets as $target) {
$key = array_search($target, $strings);
if ($key !== false) {
unset($strings[$key]);
} else {
return $target;
}
}
}
}