Assume that you have $100,000 in a bank account that is earning interest of v = 4% p.a., monthly compounding. You plan to deposit

(add) $1,000 at the end of each month, for the next fifteen years.

Then, starting in the first month of year 16, you plan to withdraw

$c per month (at the end of each month). How long will it take until the account is depleted?