#!/usr/bin/perl
use warnings;
use strict;
use Data::Dump qw(dump);
sub arith;
sub solvepart($);
sub testiterations;
sub reformat;
my $VERBOSE=shift//0;
my $MAXITERATIONS=500;
my $iterations;
my @stack;
my $num=qr/(-?\d++\.?\d*?)/;
while(<>){
	$iterations=0;
	my $given = $_;
	if ($given ~~ /exit|end|quit/i){
		die "PROGRAM TERMINATED\n";
	}
	if ($given !~ /^(\((?:[^()]++|(?-1))*+\))/){
		die "IMPROPER INPUT\n";
	}
	until ($given !~ /[()]/){
		reformat $given;
		$given =~ s/(.*)(\(\S++ ++$num ++($num)?\))/$1.solvepart($2)/e;
		testiterations;
	}
	print "\nANSWER: ".$given."\n\n";
}
sub testiterations{
	$iterations++;
	if ($iterations==$MAXITERATIONS){
		die "MAX ITERATIONS ACHIEVED: ABORTING\n";
	}
}
sub reformat($){
1 while $_[0] =~        s/(?<leading>   \((?<op>\S++)\s++$num [^()]*?\s++)
                                        (?<nums>$num\s++$num)
                                        \)
                        /$+{leading}\($+{op}\ $+{nums}\)\)/x;
}
sub solvepart($){
	my $given = shift;
	unshift(@stack, [$2,$3,$4]) while $given =~ s/(.*)\((\S++) ++(-?\d++\.?\d*?) ++(-?\d++\.?\d*?)?\)/$1/;
	if ($VERBOSE or $VERBOSE ~~ /v(?:erbose)?/i){
		print "\nDATA:\n";
		dump @stack;
	}
	return arith;
}
sub arith{
	my $value=0;
	while(@stack){
		#my @level = map{handleneg($_)}@{pop @stack};
		my @level = @{pop @stack};
		if ($level[0]eq'+'){
			$level[2]
				?($value=$level[1]+$level[2])
				:($value+=$level[1]);
		}
		elsif ($level[0]eq'-'){
                        $level[2]
                                ?($value=$level[1]-$level[2])
                                :($value=$level[1]-$value);
                }
		elsif ($level[0]eq'/'){
                        $level[2]
                                ?($value=$level[1]/$level[2])
                                :($value=$level[1]/$value);
                }
		elsif ($level[0]eq'*'){
                        $level[2]
                                ?($value=$level[1]*$level[2])
                                :($value*=$level[1]);
                }
		elsif ($level[0]eq'**'or$level[0]eq'^'){
                        $level[2]
                                ?($value=$level[1]**$level[2])
                                :($value=$level[1]**$value);
                }
		elsif ($level[0]eq'%'){
                        $level[2]
                                ?($value=$level[1] % $level[2])
                                :($value=$level[1] % $value);
                }
		else {
			die "IMPROPER INPUT\n";
		}
	}
	return $value;
}