#! /usr/bin/perl

use strict;
use warnings;

sub get_input {
    print "Type R to re-enter the values or Type E to exit:\n";
    chomp (my $value = <STDIN>);
    $value;
}

my $value = get_input();
while ($value ne 'E') { 
    if ($value eq 'R') {
	$value = get_input;
    } else {
	print 'Invalid entry, please try again\n';
	get_input;
    }
}
exit();