use strict;
use warnings;

my @events = qw(1+ 3+ 4- 5+ 5+ 6- 6- 6- 9+ 10-);
my $lastEpoch = 0;
my $conections = 0;

for (@events) {
    my ($epoch, $event) = /(\d+)(.)/;
    
    print "$lastEpoch: $conections\n" if $lastEpoch and $lastEpoch != $epoch;
    $event eq '+' ? ++$conections : --$conections;
    $lastEpoch = $epoch;
}

print "$lastEpoch: $conections\n";

##</code><code>##

1: 1
3: 2
4: 1
5: 3
6: 0
9: 1
10: 0