Ishwar lends an amount of Rs.2400 from Abdul. They agree that Ishwar will repay Abdul in the form of three annual instalments, over the period of three years, with the rates of interest being 2% for the first year, 4% for the second year, and 6% for the third year. It is known that the principal for the next year will be calculated based on the amount received at the end of the previous year. How much additional money does Ishwar need to pay at the end of three years, in the form of compound interest?