How would you solve this in C++? A Fibonacci-like sequence is a sequence of integers a₁, a₂, ... for which a_n = a_n-1+a_n-2 for all n > 2. You are given the first two elements of the sequence a₁ and a₂, and the 1-based index n. Output the n-th element of the sequence.

The input data consists of a single line which contains integers a₁, a₂ and n separated by single spaces. 0 < a₁, a₂, n < 10.

Example

input

1 2 3

output

3