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.


The input file consists of several lines. The line number i contains a single positive integer N representing the size of the i-th chessboard. [1 <= N <= 10^100]


The output file should contain the same number of lines as the input file. The i-th line should contain one number – the maximum number of bishops that can be placed on i-th chessboard without threatening each other.




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adipat: 2019-02-02 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: 2019-02-02 10:45:26
wasteacc: 2019-01-25 19:42:04

how many inputs should we take ?

indsonu: 2019-01-18 11:25:52

boost multiprecision namespace is not working can anyone suggest why?

Alexander A. Maly: 2019-01-16 19:09:08

@joeyndchandler: n = 0 is prohibited by the problem statement and does not appear in the test cases.

kaotic_lezend: 2018-12-30 11:22:32

Those who are gettin NZEC in java, read carefully. Use try catch block and catch the error NoLineException. I struggled for 3 hours then i found out that it was throwing this exception in the end of the program when it was not finding any input, so just catch that exception and that will provide an AC. //Happy Coding

yogesh1208: 2018-12-11 19:33:27

i am getting NZEC in java

deveshd2k: 2018-10-31 16:56:56

isn't the answer 2*input - 2 in python!

bloodgreed99: 2018-09-01 23:51:58

if you are doing in c++ using string then the input 5 will give ans 08 instead of 8 so make a separate case for 5 . cost me 1 WA

pavanjupalli: 2018-08-08 17:54:53

i am getting tle in c++, even i use string

joeyndchandler: 2018-07-06 10:36:43

be careful for n=0 answer is 0, though n=0 doesn't make sense still that was my only test case failing got 2 WAs :(

Last edit: 2018-07-06 10:37:16

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