def f(a,b,h):
    d=(a-b)/2
    c=(h**2+d**2)**0,5
    p=a+b+c*2
s=0
for i in range(2):
    a=int(input())
    b=int(input())
    h=int(input())
    s=s+f(a,b,h)
print(s)