Background

Description

Given three ints, a b c, one of them is small, one is medium and one is large. Return true if the three values are evenly spaced, so the difference between small and medium is the same as the difference between medium and large.

Format

Input

Output

Samples

2 4 6

true

4 6 2

true

4 6 3

false

Limitation

1s, 1024KiB for each test case.