use strict;
use warnings;

chomp(my $n = <>);

my $ans = 0;
for (my $k = 2; $k*$k <= $n; $k++) {
    while ($n % $k == 0) {
        $ans += $k;
        $n /= $k;
    }
}
$ans += $n if ($n > 1); 

print "$ans\n";