PROGRAMMING:Peanut for walnut

Little squirrel has a lot of peanuts, little bear has a lot of walnuts. Squirrels want to find bears for walnuts: 2 walnuts for every 9 peanuts.
How many walnuts can you exchange for the squirrel?
####Input format
>Number of peanuts
####Output format
>Walnut number
Note: the title guarantees that all values are in the range of int type representation.
####Input sample
```in
fifty
```
####Output sample
```out
ten
```







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