rem: if (rulenum == -1)
add: if (string_to_number(rule, 1, INT_MAX, &rulenum))
context: parse_rulenumber(const char *rule){	int rulenum = string_to_number(rule, 1, INT_MAX);	if (rulenum == -1)		exit_error(PARAMETER_PROBLEM,			   "Invalid rule number `%s'", rule);	return rulenum;}