def f(x1, y1, x2, y2, x3, y3):
    X1 = x2 - x1
    Y1 = y2 - y1
    X2 = x3 - x1
    Y2 = y3 - y1
    return abs(X2 * Y1 - Y2 * X1)/2

x1, y1, x2, y2, x3, y3 = map(int, input().split())
ans = 0
for a in [1, -1]:
    for b in [1, -1]:
        for c in [1, -1]:
            ans = max(ans, f(x1+a, y1, x2+b, y2, x3+c, y3))
            ans = max(ans, f(x1, y1+a, x2+b, y2, x3+c, y3))
            ans = max(ans, f(x1+a, y1, x2, y2+b, x3+c, y3))
            ans = max(ans, f(x1+a, y1, x2+b, y2, x3, y3+c))
            ans = max(ans, f(x1, y1+a, x2, y2+b, x3+c, y3))
            ans = max(ans, f(x1+a, y1, x2, y2+b, x3, y3+c))
            ans = max(ans, f(x1, y1+a, x2+b, y2, x3, y3+c))
            ans = max(ans, f(x1, y1+a, x2, y2+b, x3, y3+c))
            
print(ans)