Problems
Average price
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 data
First line contains number of prices n~(n \le 50). Next line contains n positive integers (no more than 10000) — the scanned prices.
Output data
Print the average of product price with 4 decimal digits.
Examples
Input example #1
3 5 7 5
Output example #1
6.0000