
use strict 'vars';
my %total;

while (<>) {
  my ($who, $action, $how_much) = split;
  unless ($how_much =~ /^\d+\.\d\d$/) {
    die "Malformed amount field";
  }

  if ($action eq 'deposit')     { $total{$who} += $how_much }
  elsif ($action eq 'withdraw') { $total{$who} -= $how_much }
  else { die "Bizarre action field `$action'" }
}

for my $customer (sort keys %total) {
  print "$customer:\t$total{$customer}.\n";
}







