def triangle(x1,y1,x2,y2,x3,y3):
    return abs((x1-x3)*(y2-y3)-(x2-x3)*(y1-y3))/2


x1,y1,x2,y2,x3,y3=map(int,input().split())
max_area=0
for A in [(x1+1,y1),(x1-1,y1),(x1,y1+1),(x1,y1-1)]:
    for B in [(x2+1,y2),(x2-1,y2),(x2,y2+1),(x2,y2-1)]:
        for C in [(x3+1,y3),(x3-1,y3),(x3,y3+1),(x3,y3-1)]:
            area=triangle(A[0],A[1],B[0],B[1],C[0],C[1])
            if area>max_area:
                max_area=area
print(max_area)