Problem:
Score : 100 points

Problem Statement

You are given a trapezoid. The lengths of its upper base, lower base, and height are a, b, and h, respectively.

An example of a trapezoid

Find the area of this trapezoid.

Constraints

1≦a≦100

1≦b≦100

1≦h≦100

All input values are integers.

h is even.

Input

The input is given from Standard Input in the following format:

a
b
h

Output

Print the area of the given trapezoid. It is guaranteed that the area is an integer.

Sample Input 1

3
4
2

Sample Output 1

7

When the lengths of the upper base, lower base, and height are 3, 4, and 2, respectively, the area of the trapezoid is (3+4)×2/2 = 7.

Sample Input 2

4
4
4

Sample Output 2

16

In this case, a parallelogram is given, which is also a trapezoid.

Solution in C (Clang 3.8.0) (judge verdict: Wrong Answer)

#include<stdio.h>

int main()
{
  int base1, base2, height, Area, Median;
 
  printf("\n Please Enter two bases and height of the trapezium \n");
  scanf("%d%d%d", &base1, &base2, &height);

  Area = 0.5 * (base1 + base2) * height;
  Median = 0.5 * (base1+ base2);

  printf("\n Area of a trapezium = %d\n", Area);
  printf("\n Median of a trapezium = %d \n", Median);

  return 0;
}