/**
* Main program.
*
* @param array $args Command-line arguments.
* @return integer Zero on success; non-zero on failure.
*/
public static function main($args)
{
printf("Application program number 6. (expression tree)\n");
$status = 0;
$expression = ExpressionTree::parsePostfix(STDIN);
printf("%s\n", str($expression));
return $status;
}
