BISHOPS  Bishops
Yesterday was Sam's birthday. The most interesting gift was definitely the chessboard. Sam quickly learned the rules of chess and defeated his father, all his friends, his little sister, and now no one wants to play with him any more.
So he decided to play with another birthday gift – a Book of Math Problems for Young Mathematicians. He opened the book somewhere in the middle and read the following problem: "How many knights can be placed on a chessboard without threatening each other?" After a while he realized that this was trivial and moved on to the next problem: "How many bishops can be placed on a chessboard without threatening each other?". Sam is in trouble here. He is not able to solve this problem and needs your help.
Sam's chessboard has size N x N. A bishop can move to any distance in any of the four diagonal directions. A bishop threatens another bishop if it can move to the other bishop's position. Your task is to compute the maximum number of bishops that can be placed on a chessboard in such a way that no two bishops threaten each other.
Input
The input file consists of several lines. The line number i contains a single positive integer N representing the size of the ith chessboard. [1 <= N <= 10^100]
Output
The output file should contain the same number of lines as the input file. The ith line should contain one number – the maximum number of bishops that can be placed on ith chessboard without threatening each other.
Example
Input: 2 3 Output: 2 4
hide comments
mrmajumder:
20200205 11:36:26
Check for the corner case, very important! 

mriow:
20191029 10:11:43
std::cin.fail() will be your friend to check for the EOF 

nikhil_sarda:
20190826 14:48:00
as far as the input is concerned,use getline(cin,<string_name>) ,and while <string_name>!="",


sanket17:
20190708 11:50:40
Use try except in python


kkksc04:
20190609 05:10:19
why python 2*n2 can't AC? Who can tell me? Thanks a lot! Last edit: 20190609 05:10:45 

jackobek:
20190430 00:21:48
becouse of endl 3 WA 

aj_254:
20190423 20:54:36
my 50th on spoj....all 50 in python ... i make myselt the pythonist. checkout my github rajat_254 for spoj python solutions


Aahitagni Mukherjee:
20190419 22:09:53
take care of corner case. Also use C++14 if you're using boost multiprecision library. 

alpish1:
20190327 15:45:17
how many inputs do we have to take in this problem its not specified. 

adipat:
20190202 10:45:18
Very simple problem, just focus on finding the pattern. If you're using Python, don't use input(), instead use sys.stdin.readlines(). Last edit: 20190202 10:45:26 
Added by:  Roman Sol 
Date:  20050417 
Time limit:  1s 
Source limit:  10000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All 
Resource:  IPSC 2004 