$n = trim(fgets(STDIN));
$numstr = trim(fgets(STDIN));
$nums = explode(" ",$numstr);
sort($nums);
$act = 0;
$tail = strlen($numstr);
for($n--;$n > 0;$n--) {
    $pos = strpos($numstr, $nums[$n]);
    if($pos > $tail) {
        $n++;
        break;
    }
    $tail = $pos;
}
echo $n;
echo PHP_EOL;