x1, y1, x2, y2, x3, y3 = map(int, input().split())
def triangle_area(x1, y1, x2, y2, x3, y3):
    return 0.5 * abs((x1 - x3) * (y2 - y3) - (x2 - x3) * (y1 - y3))

def plusminus(k, x, y):
    if k == 0:
        x += 1
    elif k == 1:
        x -= 1
    elif k == 2:
        y += 1
    else:
        y -= 1
    return x, y
def minusplus(k, x, y):
    if k == 0:
        x -= 1
    elif k == 1:
        x += 1
    elif k == 2:
        y -= 1
    else:
        y += 1
    return x, y
ans = -float("inf")
for i in range(4):
    x1, y1 = plusminus(i, x1, y1)
    for j in range(4):
        x2, y2 = plusminus(j, x2, y2)
        for k in range(4):
            x3, y3 = plusminus(k, x3, y3)
            ans = max(ans, triangle_area(x1, y1, x2, y2, x3, y3))
            x3, y3 = minusplus(k, x3, y3)
        x2, y2 = minusplus(j, x2, y2)
    x1, y1 = minusplus(i, x1, y1)
print(ans)