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## 题目描述

The Fibonacci sequence of numbers is known: F1 = 1; F2 = 1; Fn+1 = Fn + Fn-1, for n>1. You have to find SUM(K) - the sum of the first K Fibonacci numbers.

## 输入

Each line contains a natural number K (0<K<38).

## 输出

For each case, output SUM(K) in one line. You may assume the result will be in the range of 32-bit signed integer

## 样例输入

5
9


## 样例输出

12
88


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