So you mean (to quote from my earlier post) "A list indicating the number of concurrent users whenever that number changes". Something like this:

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";
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Prints:

1: 1
3: 2
4: 1
5: 3
6: 0
9: 1
10: 0
[download]