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.
params = [int(input()) for i in range(3)]

a = params[0]
b = params[1]
h = params[2]

print((a + b)*h/2)

params = [int(input()) for i in range(3)]

a = params[0]
b = params[1]
h = params[2]

print(int((a + b)*h/2))
