# 2013 Petrozavodsk, February 2

# Boss, I Can See You!

*— Oh, Boss, I can see you!*

*— Analogously!*

*From the animated film 'Investigation Held by Kolobki'*

During their investigation, detectives Boss and Colleague got into an empty warehouse to look for evidence of crime. The warehouse is a polygon without self-intersections and self-tangencies, not necessarily convex. The detectives investigate the territory of warehouse in such a way that each of them can always see the other one. Boss and Colleague can see each other if all the points of a segment connecting them lie either inside the warehouse or on its border. Find the maximal possible distance between the detectives.

**Input**

The first line contains an integer the number **n** (**3 **≤ **n **≤ **200**) of vertices of the polygon. Next **n **lines contain two integers **x _{i}**,

**y**each: coordinates of vertices in clockwise or counterclockwise order (-

_{i}**1000**≤

**x**,

_{i}**y**≤

_{i}**1000**). It is guaranteed that polygon has neither self-intersections nor self-tangencies.

**Output**

Output the maximal possible distance between Boss and Colleague. The answer must be given with absolute or relative error not exceeding **10 ^{−6}**.

4 0 0 0 1 1 1 1 0

1.4142135624