#!/usr/bin/perl

use strict;
use warnings;

my $n = <>;
my $str = <>;
chomp $str;
my @array = split / /, $str;
my $count = 0;
@array = sort @array;

my $i = 0;
while($i < $n) {
	my $j = 1;
	while(($i + $j < $n)and($array[$i] == $array[$i + $j])) {
		$j++;
	}
	if($j == 1) {
		$count++;
	}
	$i += $j;
}

print "$count\n";

exit;