KPSUM - The Sum

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One of your friends wrote numbers 1, 2, 3, ..., N on the sheet of paper. After that he placed signs + and - between every pair of adjacent digits alternately. Now he wants to find the value of the expression he has made. Help him.

For example, if N=12 then +1 -2 +3 -4 +5 -6 +7 -8 +9 -1+0 -1+1 -1+2 = 5

Input

Each line contains one integer number N (1≤ N ≤ 1015). Last line contains 0 and shouldn't be processed. Number of lines in the input does not exceed 40.

Output

For every line in the input write the answer on a separate line.

Example

Input:
12
0

Output:
5

hide comments
abdou_93: 2013-11-18 02:57:49

@The new guy.. yes the ans for 10^15
= 409090909090909

Sandeep Pathry: 2013-05-31 06:31:38

Last edit: 2013-05-31 06:55:30
The new guy: 2012-01-09 12:12:43

Is the ans for 10^15 = 409090909090909 ?? Please help someone!!


Added by:Pavel Kuznetsov
Date:2007-03-26
Time limit:0.114s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ERL JS-RHINO NODEJS PERL6 VB.NET
Resource:Vologda 2007