CF851B.Arpa and an exam about geometry

Arpa is taking a geometry exam. Here is the last problem of the exam.

You are given three points $a,b,c$ .

Find a point and an angle such that if we rotate the page around the point by the angle, the new position of $a$ is the same as the old position of $b$ , and the new position of $b$ is the same as the old position of $c$ .

Arpa is doubting if the problem has a solution or not (i.e. if there exists a point and an angle satisfying the condition). Help Arpa determine if the question has a solution or not.

The only line contains six integers $a_{x},a_{y},b_{x},b_{y},c_{x},c_{y}$ ( $|a_{x}|,|a_{y}|,|b_{x}|,|b_{y}|,|c_{x}|,|c_{y}|<=10^{9}$ ). It's guaranteed that the points are distinct.

Print "Yes" if the problem has a solution, "No" otherwise.

You can print each letter in any case (upper or lower).

In the first sample test, rotate the page around $(0.5,0.5)$ by .

In the second sample test, you can't find any solution.