use strict;
use warnings;

my $input = <<IN;
nick 5
nick 10
nick 20
john 78
erik 9
erik 12
IN
my %hits;

open my $fin, '<', \$input;

while (my $line = <$fin>) {
    next if $line !~ /^(\w+)\s+(\d+)/;
    $hits{$1} //= $2;
}

print "$_: $hits{$_}\n" for sort keys %hits;

##</code><code>##

erik: 9
john: 78
nick: 5