ACE Hardware is developing a schedule for its employees. Currently, this store has five employees and is opened from 12pm to 9pm. The store must always have at least two people on hand. Each employee must work at least four hours and no more than eight hours each day. Employee 1 goes to school and cannot start before 4pm. Thus, employee 1 earns $10 per hour while all other employees earn $12 per hour.

Assume that employees are required to work consecutive hours.

Formulate an optimization model for this problem.