Description

Here's a brain teaser: "A store has a rule: three empty soda bottles can be exchanged for one full bottle of soda. If Xiao Zhang has ten empty bottles, how many bottles of soda can she drink at most?" The answer is $5$ bottles, as follows: first exchange $9$ empty bottles for $3$ full bottles, drink them, leaving $4$ empty bottles. Then exchange $3$ empty bottles for $1$ full bottle, drink it, leaving $2$ empty bottles. Then borrow one bottle from the store owner, drink it, and use the $3$ empty bottles to exchange for one full bottle to return to the owner. If Xiao Zhang has $n$ empty bottles, how many bottles of soda can she drink at most?

Input Format

Each line contains a positive integer $n$ ($1 ≤ n ≤ 100$), representing the number of empty bottles Xiao Zhang has. $n=0$ indicates the end of input, and your program should not process this line.

Output Format

For each test case, output one line containing the maximum number of bottles of soda that can be drunk. If no bottles can be drunk, output $0$.

Sample

3
10
81
0

1
5
40