_{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 .

**Input Format**

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.

**Constraints**

**Output Format**

Output exactly one real number which is the answer to the problem.

**Sample Input 0**

```
0 30
```

**Sample Output 0**

```
1.473849410
```