A married couple, Simon and Maria, seek advice from you on their retirement life. Simon is 65 years old and Maria is 62, and they wish to retire on a comfortable amount. Simon's life expectancy at age 65 is 20 years and Maria's life expectancy at age 62 is 28 years. Assume both of them want to retire this year. How much will need for their retirement? Provide all your assumption for the calculation.