CRS - Crying Series

Monir is a student of class 8. He loves to learn new logic from Mathematics. Divergent Geometric Series is an interesting topic to him. So, He starts practicing to find the sum of the series in his everyday life. So he pick a standard series for Nth term,

F(x) = (-1)*1 + (-1)2* 2 + (-1)3* 3 + ..... + (-1) N*N

In this case, He asks for your help to find the value (algebraic sum) of F(x) from given series. As you are a great programmer in our country.

Input

Every line of the input contains N.

Constraints

  • 0 ≤ N ≤ 1015

Output

For each test case, print a single line and the value (algebraic sum of all elements) of F(x) from given series.

Example

Input:
0
1
2

Output:
0
-1
1

Added by:asad_IT
Date:2018-06-24
Time limit:0.300s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All
Resource:Math

hide comments
2020-05-10 13:48:30
use while(cin >> n) to take input. Input contains multiple lines
2018-07-02 14:36:30 asad
thanks. @wisfaq
2018-06-24 15:25:11 wisfaq
Be careful:
the sentence : The first line of the input contains a single integer N denoting the number of terms in the series is not correct.
every line of the input contains an N.
So process to eof.
Why have others with AC not mentioned this?
2018-06-24 14:09:38 asad
ok
2018-06-24 13:24:17
should be moved to tutorial
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