(c) The total cost to the Department of Homeland Security of any such conference shall not exceed $500,000. (d) Employees who attend a conference virtually without travel away from their permanent duty station within the United States shall not be counted for purposes of this section, and the prohibition contained in this section shall not apply to payments for the costs of attendance for such employees. 522. None of the funds made available in this Act may be used to reimburse any Federal department or agency for its participation in a National Special Security Event. 523. (a) None of the funds made available to the Department of Homeland Security by this or any other Act may be obligated for the implementation of any structural pay reform or the introduction of any new position classification that will affect more than 100 full-time positions or costs more than $5,000,000 in a single year before the end of the 30-day period beginning on the date on which the Secretary of Homeland Security submits to Congress a notification that includes— (1) the number of full-time positions affected by such change