a = int(eval(input()))

b = int(eval(input()))

c = int(eval(input()))



print(((a+b)*c//2))
a = int(eval(input()))

b = int(eval(input()))

h = int(eval(input()))



print(((a+b)*h//2))
a = int(eval(input()))
b = int(eval(input()))
c = int(eval(input()))
print(((a + b) * c // 2))

a = int(eval(input()))
b = int(eval(input()))
h = int(eval(input()))
print(((a + b) * h // 2))

-c = int(eval(input())) -print(((a + b) * c // 2)) +h = int(eval(input())) +print(((a + b) * h // 2))