# use strict;
# use warnings;

<>;
chomp(my $s = <>);
my @As = split(/\s/, $s);
my %d;
foreach (@As) {
    $d{$_} = 0 if !exists($d{$_});
    $d{$_}++;
}
my $c = 0;
foreach (values(%d)) {
    $c++ if $_ == 1;
}
print($c, "\n");