Problems

# Waterpipe - 2

# Waterpipe - 2

In the plan area is depicted **N** cottages, which have known coordinates **X**, **Y** (**i** = **1** .. **N**). What is the minimum length should be the total length of water pipes that connects all the houses **N** of the town, directly or through several intermediate houses?

**Input**

The first line number **N** - the number of houses. The next **N** lines coordinates cottages **X**, **Y** (**i** = **1** .. **N**). All input values are natural numbers not greater than **100**.

**Output**

Single number - the total length of water pipes, rounded to integers.

Input example #1

7 3 4 4 3 1 3 3 5 2 3 2 2 1 1

Output example #1

7