1. A professor from the Department of Mathematical Modeling at FEFU last academic year gave 6480 twos, thereby overachieving the commitments taken at the beginning of the year. In the next academic year, the number of professors increased by 3, and each of them started giving more twos. As a result, a new record was set for enclosed spaces: 11200 twos in a year. How many professors were there initially, if each professor gives the same number of twos as the others during the session?