use strict;
use warnings;
use utf8;

my $N = <STDIN>;
my $nums = <STDIN>;
my $answer = 0;

chomp $nums;

my @A = split / /, $nums;

@A = sort {$b <=> $a} @A;

for( my $i = 0; $i < ((scalar @A) - 1); $i++) {
    if ($A[$i] == ($A[$i + 1] + 1)) {
        $A[$i] = 0;
    }
    $answer += $A[$i];
}

$answer += $A[(scalar @A) - 1];

print $answer;