### Example: calculating a trapezoid area

Let us write a program that takes the lengths of the two bases of a trapezoid and its height (one floating-point number per row) and calculates the area of the trapezoid by the standart math formula:

var b1 = double.Parse(Console.ReadLine());
var area = (b1 + b2) * h / 2.0;
Console.WriteLine("Trapezoid area = " + area);


If we start the program and enter values for the sides 3, 4 and 5, we will receive the following result:

3
4
5
Trapezoid area = 17.5


#### Testing in the Judge System

Test your solution here : https://judge.softuni.bg/Contests/Practice/Index/504#4.