Score : $100$ points
Three poles stand evenly spaced along a line. Their heights are $a$, $b$ and $c$ meters, from left to right. We will call the arrangement of the poles beautiful if the tops of the poles lie on the same line, that is, $b-a = c-b$.
Determine whether the arrangement of the poles is beautiful.
Input is given from Standard Input in the following format:
$a$ $b$ $c$
YES if the arrangement of the poles is beautiful; print
2 4 6
Since $4-2 = 6-4$, this arrangement of poles is beautiful.
2 5 6
Since $5-2 \neq 6-5$, this arrangement of poles is not beautiful.
3 2 1
Since $1-2 = 2-3$, this arrangement of poles is beautiful.