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Time Limit: 1.0 s

Memory Limit: 512.0 MB

Description

There is a strange shop in Seriousland which sells chocolates at a rate of 1 taka per chocolate.
But the strange thing is anyone can get a chocolate from the shop in exchange of 2 empty chocolate packet.

If you have \(N\) taka, then how many chocolates you can eat in total ?

Input

Only one integer \(N\)
\(1 <= N <= 100\)

Output

one integer : maximum number of chocolate you can eat with \(N\) taka.

Sample

5

9

first of all you can buy 5 chocolate from the shop, after eating all the chocolates you will have 5 empty packet of chocolate.
then you can buy 2 chocolate in exchange of 4 empty chocolate. After eating 2 chocolate you will have 3 empty packets.
then you can buy 1 more chocolate in exchange of 2 empty packet and will have 2 empty packet after eating the current chocolate.
finally you can buy one more chocolate using remaining 2 empty packet and after eating the chocolate you will left with only one empty packet.

so in total you can eat 5 + 2 + 1 + 1 = 9 chocolate