PROGRAMMING:Lawn improvement

There is a square lawn with a length of N and a width of 2. Now it is covered with a square lawn with a length of 2 and a width of 1. How many different paving methods are there?
###Input format:
Enter a positive integer n (1 = < n < = 90) to represent the length of the turf.
###Output format:
Output the number of different paving methods.
###Input example:
```in
three
```
###Output example:
```out
three
```







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