<?php
$n = trim(fgets(STDIN));
$numstr = trim(fgets(STDIN));
$nums = explode(" ",$numstr);
sort($nums);
$act = 0;
$tail = strlen($numstr);
while(($num = array_pop($nums)) !== null) {
    $pos = strpos($numstr, $num);
    if($pos > $tail) {
        array_push($nums,$num);
        break;
    }
    $tail = $pos;
}
echo count($nums);
echo PHP_EOL;