#!/usr/bin/perl

use strict;

chomp (my $equation = <DATA>);
my @stack;

foreach ( split(/\s*,\s*/, $equation) ) {

  push(@stack,$_), next if /\d+/;
  die "stack underrun" if @stack < 2;

  my ($val1, $val2) = (pop(@stack), pop(@stack));
  push(@stack, $val1 + $val2), next if $_ eq '+';
  push(@stack, $val1 * $val2), next if $_ eq 'x';

  die "undef. operator ($_)";
}

print "Result (stack): ", join(", ", @stack), "\n";


__DATA__
1,2,3,4,+,5,+,x,6, ......  x,x,x,x,x,9164,x,+,9165,9166,91    <--- your input as a single line

Result (stack): 1, 144, 1.9792773969506e+27, 6.22437334578068e+26, 5.77209920038837e+273, 8966, 4.97957520221034e+261, 9165, 9166, 91