PROGRAMMING:ZF series's seclusion

Finally, he defeated the demon king and got the beauty back. ZF's name was also praised by the people of Holy Spirit ancient land. He finally experienced the addiction of idols. ZF thought, as an idol, what should be left behind.
So he left a sword Qi decision, later people can understand this formula, can master without sword without me, can have half of his strength.
After leaving the secret script, I heard a roar. I only heard that the world was so big. I wanted to have a look. From then on, there was no news.
For a long time, there are only the first two moves left, but the later moves are evolved from the first two. The first move can emit one sword Qi, the second move can emit two sword Qi, and the third move can emit the number of sword Qi
It is the sum of the first two forms. By analogy, we can find the number of sword Qi in the nth form.
###Input format:
A number n
###Output format:
How many sword Qi are there in the N style
###Input example:
Here is a set of inputs. For example:
```in
one
two
three
```
###Output example:
The corresponding output is given here. For example:
```out
one
two
three
```







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