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
verseth:
20210415 12:20:44
If you're using Ruby then you can very easily iterate through the input lines indefinitely (reads all the lines it's given) by using:


aditigedam:
20200902 13:44:50
for taking input use


amar_shukla1:
20200720 18:51:46
take sc.hasNextBigInteger()


wargang:
20200623 07:06:21
took some WA's. but really worth it. 

vansh_1610:
20200603 08:28:35
how many test cases we have to take?? 

ocean_bh11:
20200520 21:42:42
Use sc.hasNextBigInteger() for taking test cases in java 

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

Added by:  Roman Sol 
Date:  20050417 
Time limit:  1s 
Source limit:  10000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All 
Resource:  IPSC 2004 