Underground Cables#1387
The city plans to eliminate unattractive electrical poles by laying cables underground. A list of points that must be connected is given, but there are certain constraints. The tunneling equipment can move only along straight lines between the specified points. At any location other than the given points, at most one underground cable may pass, therefore no two cables are allowed to intersect.
A set of points is given. Determine the minimum total length of cable required so that every pair of points is connected either directly or through other points.
Contains multiple test cases. Each test case begins with an integer n~(2 \le n \le 1000) — the number of points in the city. Each of the following lines contains two integers and y~(-1000 \le x, y \le 1000) — the coordinates of a point . All points within a single test case are distinct. The last line contains and should not be processed.
For each test case, print one real number — the minimum length of cable required to connect all city points, printed with accuracy to two decimal places.
Example 1