For a special 20-year temporary life annuity-due payable monthly on (50), you are given:

- Mortality follows the Illustrative Life Table with = 0.06.

- Deaths are uniformly distributed over each year of age.

- 100 is payable at the beginning of each month from age 50 for 10 years.

- 400 is payable at the beginning of each month from age 60 for 10 years.

Calculate the expected present value of these annuity payments.