e = list(map(int, input().split()))

e.sort()

print((int(e[0]*e[1]*(1/2))))
a, b, c = list(map(int, input().split()))

print((int(a*b/2)))
e = list(map(int, input().split()))
e.sort()
print((int(e[0] * e[1] * (1 / 2))))

a, b, c = list(map(int, input().split()))
print((int(a * b / 2)))

-e = list(map(int, input().split())) -e.sort() -print((int(e[0] * e[1] * (1 / 2)))) +a, b, c = list(map(int, input().split())) +print((int(a * b / 2)))