This problem is a programming version of Problem 197 from projecteuler.net
Given is the function ( is the floor-function), the sequence is defined by and .
Find for with given and . Your answer would be considered correct if it has absolute error not more than .
Every test file contains two real numbers: and with no more than two digits after decimal point. These numbers are situated in a single line and are separated by a single space.
Output exactly one real number which is the answer to the problem.
Sample Input 0
Sample Output 0