PROGRAMMING:One step, two steps

You have to cross the river, but there is no bridge. There is only a stone road made of a row of stones. You can only cross one stone or two stones at a time. How many ways can you go to the nth stone.
###Input format:
Positive integer n
###Output format:
The number of possibilities
###Input sample 1:
Here is a set of inputs. For example:
```in
one
```
###Output sample 1:
The corresponding output is given here. For example:
```out
one
```
###Input sample 2:
Here is a set of inputs. For example:
```in
two
```
###Output sample 2:
The corresponding output is given here. For example:
```out
two
```
###Input sample 1:
Here is a set of inputs. For example:
```in
eight
```
###Output sample 1:
The corresponding output is given here. For example:
```out
thirty-four
```







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