x1,y1,x2,y2,x3,y3 = map(int,input().split())
s = 0
def f(x,y,z):
    if z==0: x -= 1
    if z==1: x += 1
    if z==2: y -= 1
    if z==3: y += 1
    return x,y
def g(x1,y1,x2,y2,x3,y3):
    return abs((x2-x1)*(y3-y1)-(x3-x1)*(y2-y1))/2
for i in range(4):
    x4,y4 = f(x1,y1,i)
    for j in range(4):
        x5,y5 = f(x2,y2,j)
        for k in range(4):
            x6,y6 = f(x3,y3,k)
            s = max(s,g(x4,y4,x5,y5,x6,y6))
print(s)