#!/usr/bin/perl



use strict;

my @array;
my $i;
my $response;
my $sum=0;

#  PART A

for($i=0  ; $i<20    ; $i++)
{
	$array[$i]=(4*$i)+4;
}


# PART B

do
{
	print "Please enter a number between 0 and 19 inclusive ";
	$response=;
	chomp($response);
	if (($response<0) || ($response>19) )
	{
		print "\nError on input. Number must be between 0 and 19 inclusive\n";
		print "Please re-enter\n";
	}



} until ( (0<=$response)   && ($response <=19) );


print "Number is $array[$response]\n";


# PART C

for($i=0   ; $i<=$response  ; $i++)
{
	$sum=$sum+$array[$i];
}
print "The sum is $sum\n";