Input (grade 13): Zoroastrianism was the dominant religion of Sassanid Persia, and Mazdak himself was a Zoroastrian priest, or mobed, but most of the Zoroastrian clergy regarded his teaching as a heresy.
Output (grade 9): Zoroastrianism was the dominant religion of Sassanid Persia. Mazdak was a Zoroastrian priest.