def area(XY):
    dx1 = XY[1][0] - XY[0][0]
    dy1 = XY[1][1] - XY[0][1]
    dx2 = XY[2][0] - XY[0][0]
    dy2 = XY[2][1] - XY[0][1]
    return abs(dx1 * dy2 - dx2 * dy1) / 2


x1, y1, x2, y2, x3, y3 = map(int, input().split())
XY = [[x1, y1], [x2, y2], [x3, y3]]
ans = 0

add = [(0, 1), (0, -1), (1, 0), (-1, 0)]
for i in range(4):
    XY[0][0] += add[i][0]
    XY[0][1] += add[i][1]
    for j in range(4):
        XY[1][0] += add[j][0]
        XY[1][1] += add[j][1]
        for k in range(4):
            XY[2][0] += add[k][0]
            XY[2][1] += add[k][1]
            ans = max(ans, area(XY))
            XY[2][0] -= add[k][0]
            XY[2][1] -= add[k][1]
        XY[1][0] -= add[j][0]
        XY[1][1] -= add[j][1]
    XY[0][0] -= add[i][0]
    XY[0][1] -= add[i][1]

print(ans)