a,b,c = list(map(int,input().split()))

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

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

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

-a, b, c = list(map(int, input().split())) +a, b, c = sorted(map(int, input().split()))