John's son is about to start primary school in a private school. At the moment, the tuition is $20,000 per year, payable at the start of the school year (t=0). John expects tuition costs to increase, on average by 5% per year over the next 13 years (t=1 to t=13). This means that his private education has 14 years, and the last payment of tuition fee is due at the beginning of year 14 (t=13). John has a saving's account which is assigned to paying his son tuition cost. How much money at least should the saving account have today (t=0) so that the 14-year tuition cost can be fully paid using money from the saving's account only? Assume that John's son remains in this private school for the entire 14-year years of his private education and that John's current annual interest rate is 6%.