A perpetuity with annual payments is payable beginning 5 years from now. The first payment is 50. Each annual payment thereafter is increased by 5 until a payment of 150 is reached. Subsequent payments remain level at 150. This perpetuity is purchased by means of 5 annual premiums, with the first premium of P due immediately. Each premium after the first is 106% of the preceding one. The annual effective interest rates are 6% during the first 4 years and 3% thereafter. Calculate P.