#162. Trapezoid area
You get the bases a, b and the height h of a trapezoid. Print its area (`(a + b) * h / 2`) with 1 decimal place.
### Input
Each on its own line: a, b, h (1 ≤ value ≤ 30).
### Output
A decimal number.
Examples
Input
19 20 15
Output
292.5
Input
27 12 19
Output
370.5
💡 You can solve it with Python, JavaScript or blocks. Read the input line by line with input(). Don't print a question (like input("Number: ")). Print exactly what the output asks for, nothing more.