Average price

You have scanned the prices of several products for sale. You now wish to determine the average product price. Unfortunately, you know that you have been sloppy, and you may have scanned some products more than once. However, you know that you have scanned every product at least once, and that no two products have exactly the same price. Find the average of product price.

Input

First line contains number of prices $n(n\le 50)$. Next line contains $n$ positive integers (no more than $10000$) — the scanned prices.

Output

Print the average of product price with $4$ decimal digits.

Examples