Challenge of Bravery

Time Limit: 10 Seconds    Memory Limit: 32768 KB

Background

I am at a gate, there're some words on the gate: "Brave boy! You have passed all the dangers, and I've waited for you for years! Finally, you came."

"This is the gate to your heart! Before going on, I still want to have a test on you, first is your bravery."

The gate disappeared; left some stones floating in the sky...

And a monster came...

Problem

There're N (N <= 50) stones. I can step on it, and after I stepped on it, it will disappear. Of course, the monster is running after me! I must touch on each stone exactly once, and step on any other stone, and the monster will fall into the dark. I want to finish it as quickly as possible. Time I needed is the distance between the stones.

I'm at stone 1 at first.

Input

This problem contains multiple test cases.

Each test case begins with an integer N, then followed by N lines, each lines contains 3 numbers: x, y, z, representing the coordinate of the stones. I can step on any stone at last except 1.

Output

For each test case, output the minimum distance, having 1 digit after radix point.

Sample Input

2
1 1 1
2 2 2

Sample Output

1.7

Submit

Source: JIANG, Yanyan's Contest #2