sub yn
{
    my $prompt = shift;

    my $t = $|;
    $| = 1;

    my $result = 0;
    my $answer;
    print $prompt;
    do
    {
	chop($answer = <STDIN>);
	if ($answer eq "y")
	{
	    $result = 1;
	}
	elsif ($answer eq "n")
	{
	    $result = 0;
	}
	else
	{
	    print "Please enter y or n: ";
	}
    }
    while (($answer ne "y") && ($answer ne "n"));

    $| = $t;
    $result;
}