Description

Given the first two terms $a_1$ and $a_2$ of an arithmetic sequence, determine the $n$th term.

Input Format

Input consists of a single line with three integers $a_1$, $a_2$, and $n$. The constraints are $-100 \le a_1, a_2 \le 100$ and $0 < n \le 1000$.

Output Format

Output a single integer representing the value of the $n$th term.

Sample

1 4 100

298