def load_point():
    a, b = map(int, input().split())
    return a + b * 1j


a = load_point()
b = load_point()
c = load_point()

def dej_velikost(target, a, b):
    c = (a + b) / 2
    r = abs(a - b) / 2
    real = abs(target - c)
    return abs(real - r)


res = [dej_velikost(c, a, b), dej_velikost(a, c, b), dej_velikost(b, a, c)]
print(min(res))