Background
At the team competition of the 10th national student informatics Olympic, which is organized at Hanoi National University, there are N teams participating. Each team is assigned to work in a camp. On the map, it can be seen that the camps are
positioned on the vertices of a convex polygon with N vertices: P_{1}, P_{2}, …, P_{N} (the vertices are enumerated around the polygon in counterclockwise order.) In order to achieve absolute safety providing electricity to the camps, besides an electric supplying system, the host organization set up a path from a reserved electricity
generator (which is placed in one of the camps) to every camp once, and the
path's total length is minimum.
Problem
Given the coordinates of the polygons' vertices (the camps' positions), determine the length of the electric path corresponding to the host organization's arrangement.
Input
The first line contains the integer N (1 ≤ N ≤ 200). The i'th line of the next N lines contains two real numbers x_{i}, y_{i}, separated by a space, with no more than 3 digits after the decimal points, are vertex P_{i}'s coordinates on the plane (with i = 1, 2, …, N). The length of the path connecting two vertex (x_{i}, y_{i}) and (x_{j}, y_{j}) is computed with the formula: sqrt((x_{i} − x_{j})^{2} + (y_{i} − y_{j})^{2}).
Output
The only line should contain real number L (written in real number format, with 3 digits after the decimal point), which is the total length of the electric path.
Sample
input  output 

4
50.0 1.0
5.0 1.0
0.0 0.0
45.0 0.0
 50.211

Problem Source: The competition for selecting the Vietnam IOI team