EIU Programming Practices and Exams

ABC Company has just installed a new production line. The company is considering the appropriate method and rate of depreciation for each year. By design, the equipment has a shelf life of N years. In the first year, the depreciation rate is assumed to be X, the company wants the depreciation rate to decrease gradually according to the number of years of use as follows:

• First year: X
• Second year X – X*1/N
• Third year: X – X*2/N
• …

After N years of usages, the value of the equiqment is R. Caculate the initial value of X

Input

A single line has three numbers separated by a space, the corresponding number of years using N (1 ≤ N ≤ 1000), initial value C (0 < C < 10¹⁸), and residual value (0 < R < 10¹⁸) .

Output

Print out the depreciation rates for the first year with 6 decimal place accuracy

Example

Input:
5 1000000000 500000000

Output:
0.2122959