def distance(x1, y1, x2, y2):
    return ((x2 - x1)**2 + (y2 - y1)**2)**0.5
def heron_area(x1, y1, x2, y2, x3, y3):
    a = distance(x1, y1, x2, y2)
    b = distance(x2, y2, x3, y3)
    c = distance(x3, y3, x1, y1)
    s = (a + b + c) / 2
    area = (s * (s - a) * (s - b) * (s - c))**0.5
    return area
x1,y1,x2,y2,x3,y3=map(int,input().split())
a=[[1,0],[-1,0],[0,1],[0,-1]]
b=[[x1,y1],[x2,y2],[x3,y3]]
c=0
for i in range(4):
	for j in range(4):
		for k in range(4):
			c=max(c,heron_area(b[0][0]+a[i][0],b[0][1]+a[i][1],b[1][0]+a[j][0],b[1][1]+a[j][1],b[2][0]+a[k][0],b[2][1]+a[k][1]))
print(c)