PROGRAMMING:Fibonacci sequence (I)

Known Fibonacci sequence $$f_{ n} = F_{ n-1} +F_{ n-2}(n>=3), F_ 1 = 1, F_ 2=1$$
The n-th term of the sequence is solved recursively.
###Input format:
Enter a positive integer n $$(1 < = n < = 40) $$.
###Output format:
Output a number, the nth item of the sequence
###Input sample 1:
```in
one
```
###Output sample 1:
```out
one
```
###Input sample 2:
```in
three
```
###Output sample 2:
```out
two
```







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