URI Online Judge | 2522
# FNDI's Network

**Timelimit: 1**

By Ricardo Oliveira, UFPR Brazil

The building of the Federal Department of Natural Islands (FDNI) is being widely reformed. Because of that, the old computer lab was destroyed, and a new one is being built on the second floor of the building.

There are **N** computers in the new lab, numbered from 1 to **N**. For each computer *i*, 1 ≤ *i* ≤ **N**, we know the position (**x _{i}**,

Your task is, given the positions of each computer in the new lab, determine the minimum total length of cable needed to build a valid network.

First line of each test case contains an integer **N** (1 ≤ **N** ≤ 500), the number of computers in the lab. Each of the next **N** lines contains two integers **x _{i}** and

The input ends with end-of-file (EOF).

For each test case, print a single line containing the minimum total length of cable needed to build a valid network. Round and print the answer with exactly two decimal places.

Input Sample | Output Sample |

4 |
12.00 |