Barb E. Dall, a flight attendant, received wages of $33,000 in 2021. The airline provided transportation on a stand-by basis, at no charge, from her home in Detroit to the airline's hub in Chicago. The fair market value of the commuting flights was $5,000. Also in 2021, Barb received payments, under an accountable plan, of $10,000 for overnight travel, but only spent $6,000. Barb became disabled in November 2021 and received worker's compensation of $4,000. What amount must Barb include in gross income on her 2021 tax return