>perl
my $answer = 42;
{
    print "What is the answer? ";
    chomp( my $input = <STDIN> );
    if ( $input == $answer ) {
        print "Good!\n";
    }
    else {
        print "Please try again.\n";
        redo;
    }
}
__END__
What is the answer? 1
Please try again.
What is the answer? 2
Please try again.
What is the answer? 42
Good!