#!/usr/bin/perl -wl
use strict;

my $errmsg = 'Invalid argument passed';

$_ = shift or die $errmsg;
s/\s+//g;
/^(\d+)[dD](\d+)([+-]\d+)?$/ or die $errmsg;
my $sum = 0;
$sum += 1 + int rand $2 for 1..$1;
$sum += $3 if defined $3;
print $sum;