use strict;

my $N = 28123;
my $sum;
my @ovdiv;

for (my $i = 2; $i < $N; ++$i) {
  my $s = 0;
  for (my $j = 1; $j <= $i / 2; ++$j) {
    if ($i % $j == 0) {
      $s += $j;
    }
  }
  if ($i < $s) {
    push(@ovdiv, $i);
  }
}
my @num = ();
for (my $i = 0; $i < $N; ++$i) {
  $num[$i] = 1;
}
for (my $i = 0; $i < @ovdiv; ++$i) {
  for (my $j = $i; $j < @ovdiv; ++$j) {
    $num[$ovdiv[$i] + $ovdiv[$j]] = 0;
  }
}
$sum = 0;
for (my $i = 0; $i < @num; ++$i) {
  if ($num[$i]) {
    $sum += $i;
  }
}
print $sum,"\n";