use strict;
use warnings;

my %yahoo = ();

while (<DATA>) {
    chomp;
    my ($value, $key) = split;
    $yahoo{$key} += $value;
}

foreach my $key (sort keys %yahoo) {
       print "$key: $yahoo{$key}\n";
}
__DATA__
12 AAAA
12 AAAA
15 BBBB
1222 CCCC
1 BBBB