is an infinite sequence of integers that satisfies to Fibonacci condition *F*_{i + 2} = *F*_{i + 1} + *F*_{i} for any integer *i*.
Write a program, which calculates the value of *F*_{n} for the given values of *F*_{i} and *F*_{j}.

### Input

The input contains five integers in the following order: *i*, *F*_{i}, *j*, *F*_{j}, *n*.

−1000 ≤ *i*, *j*, *n* ≤ 1000, *i* ≠ *j*,

−2·10^{9} ≤ *F*_{k} ≤ 2·10^{9} (*k* = min(*i*, *j*, *n*), …, max(*i*, *j*, *n*)).

### Output

The output consists of a single integer, which is the value of *F*_{n}.

### Sample

### Notes

In the example you are given: *F*_{3} = 5, *F*_{−1} = 4; you asked to find the value of *F*_{5}. The following Fibonacci sequence can be reconstructed using known values:

…, *F*_{−1} = 4, *F*_{0} = −1, *F*_{1} = 3, *F*_{2} = 2, *F*_{3} = 5, *F*_{4} = 7, *F*_{5} = 12, …

Thus, the answer is: *F*_{5} = 12.

**Problem Source: **Quarterfinal, Central region of Russia, Rybinsk, October 17-18 2001