BEENUMS  Beehive Numbers
A beehive is an enclosed structure in which some honey bee species live and raise their
young. In this problem we consider a twodimensional sketch of the beehives. Each
beehive is composed of a certain number of cells, where each cell is a regular hexagon.
Each cell may have some neighbors, which are other cells that share a side with that cell.
A cell with exactly 6 neighbors is an internal cell, while a cell with fewer neighbors is an
external one. Notice that an external cell can always be changed to internal by adding
some neighbor cells.
We are interested in a particular class of beehives. This class of valid beehives is defined
recursively as follows: a) a single cell is a valid beehive; and b) given a valid beehive B,
if we add the minimum number of cells such that each external cell of B becomes an
internal cell, the result is a valid beehive.
The number of cells in a valid beehive is called a beehive number. Given an integer N ,
you must decide whether it is a beehive number.
Input
Each test case is described using a single line. The line contains an integer N (1 ≤ N ≤
10^{9} ). The end of input is indicated with a line containing a single −1.
Output
For each test case, output a single line containing an uppercase “Y” if N is a beehive
number, or an uppercase “N” otherwise.
Example
Input:
43
1
7
19
15
1
Output:
N
Y
Y
Y
N
hide comments
amulyagaur:
20170311 12:31:05
those who are not able think of direct solution should try binary search


vanvinhbk94:
20170218 16:46:06
Very easy 

nilabja16180:
20170215 16:46:33
Very easy, search for beehive number for hint!


holmesherlock:
20170118 14:33:03
I guess there is some problem with the problem statement,,but after some description in the comment section it is easy to solve..


scorpion_ajay:
20170111 16:03:38
a piece of cake :p 

imperfectboy:
20170107 08:27:29
one of the easiest problem :D Don't think too much !!! 

srihari_v:
20170104 19:53:49
my 26th


esshuvo:
20161216 11:17:24
Most confusing problem ever i have solved!Though i solved this using binary search,but till now didn't get this what problem setter said by this " In this problem we consider a twodimensional sketch of the beehives. Each


spartax:
20161206 22:30:34
See the sequence 1, 1 + 6, 1 + 6 + 12, ... and you will get the solution 

Simran Saha:
20161118 08:03:47
I am having difficulty in understanding the problem. Can anybody give a better explanation? 
Added by:  Pablo Ariel Heiber 
Date:  20100926 
Time limit:  0.666s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 NODEJS OBJC VB.NET 
Resource:  FCEyN UBA ICPC Selection 2010 