#! /usr/bin/env perl6

my %population = (Oslo          => 500_000, 
                  Xyflwizz      => "unknown",
                  Somewhere     => -100,
                  Paris         => 5_000_000,
                 "Buenos Aires" => 10_000_000);

subset PositiveInt of Int where * > 0;

my $total = %population.values.grep(* ~~ PositiveInt).sum;

say "Total population: $total";