PROGRAMMING:Part 3: show your IQ
After passing the previous two levels, youyou Xuejie's team felt that "this is an era of intelligence show". This is not the third level, but actually met a boss three who shows the lower limit of intelligence. The boss said to youYou Xuejie and her party, "I'm specializing in Mathematics in the demon world recently, and I still have the last difficult serial problem on hand. A1 = 1 / 4, A2 = 1, A3 = 9 / 4,..., an = n ^ 2 / 4, if you find their sum, I'll let you go, otherwise heiheiheihei... "It's not easy to meet a boss with such a low IQ, and youyou Xuejie is drunk. As a member of youyou Xuejie team, let you dominate the life and death power of your team.
###Input format:
There are several groups of test data, and a number in each line represents n (n < = 100000).
When n equals 0, the program ends.
###Output format:
Output Sn with 2 decimal places.
###Input example:
Here is a set of inputs. For example:
```in
one
two
three
0
```
###Output example:
The corresponding output is given here. For example:
```out
zero point two five
one point two five
three point five zero
```
answer：If there is no answer, please comment
###Input format:
There are several groups of test data, and a number in each line represents n (n < = 100000).
When n equals 0, the program ends.
###Output format:
Output Sn with 2 decimal places.
###Input example:
Here is a set of inputs. For example:
```in
one
two
three
0
```
###Output example:
The corresponding output is given here. For example:
```out
zero point two five
one point two five
three point five zero
```
answer：If there is no answer, please comment