local t = {}
t[1] = {io.read("*n", "*n")}
t[2] = {io.read("*n", "*n")}
t[3] = {io.read("*n", "*n")}

local function solve(A, B, C, D, E, F)
  C, E = C - A, E - A
  D, F = D - B, F - B
 return  math.abs(C * F - D * E)
end

local ans = 0
for i = 0, 63 do
  local v = i
  local s = {}
  for j = 1, 3 do
    s[j] = {t[j][1], t[j][2]}
    if v % 4 == 0 then
      s[j][1] = s[j][1] + 1
    elseif v % 4 == 1 then
      s[j][1] = s[j][1] - 1
    elseif v % 4 == 2 then
      s[j][2] = s[j][2] + 1
    else
      s[j][2] = s[j][2] - 1
    end
    v = math.floor(v / 4)
  end
  ans = math.max(ans, solve(s[1][1], s[1][2], s[2][1], s[2][2], s[3][1], s[3][2]))
end
print(ans / 2)