#!/usr/bin/env perl

use strict;
use warnings;
use feature 'say';

sub do_calc {
	my ($op, $acc, @args) = @_;
	for my $arg (@args) {
		$acc += $arg if $op eq '+';
		$acc -= $arg if $op eq '-';
		$acc *= $arg if $op eq '*';
		$acc /= $arg if $op eq '/';
	}
	return $acc;
}

sub calc {
	my $exp = shift;
	die 'oops!' unless $exp =~ m/\(([\+-\/\*])([0-9 \.-]+)\)/;
	return do_calc($1, split ' ', $2);
}

sub pn {
	my $exp = shift;
	my $old = $exp;
	$exp =~ s/(\([\+-\/\*] [0-9 \.-]+\))/calc($1)/eg;
	die "oops! i'm stuck" if $exp eq $old;
	return $exp if $exp =~ m/^[0-9 \.-]+$/;
	return pn($exp);
}

say pn($ARGV[0]);