One day Xiao Ming is not happy because he has no idea about how to run out of his pocket money. At that moment, a mysterious man appears with a smile: "My keys are on sale. one key cost $3$ yuans and $3$ keys cost $10$ yuans. How many keys do you wanna buy?"

Xiaoming is attracted by mysterious man and wants to spend all his money on buying keys. He doesn't want keep any money at the end. At the same time, because of the heavy weight of keys, Xiaoming Hopes that he can buy as few keys as possible. At the beginning, Xiao Ming had $n$ yuan. Can you tell Xiaoming the minimum number of keys he can bought if he runs out of his pocket money? If Xiaoming can't run out of his money, please output "orz".

The first line contains one integer $n(1 ≤n ≤10^9)$, the pocket money Xiaoming have.

If Xiaoming can't run out of his money, please output "orz", otherwise output the minimum number of keys he can bought if he runs out of his money.

For the first case, Xiaoming can spend 3 yuan to buy a key.
For the second case, it's impossible to run out of his money.