import math

x1 = float(input()) 
y1 = float(input())
x2 = float(input())
y2 = float(input())
x3 = float(input())
y3 = float(input())

side1 = math.sqrt((x2 - x1)**2 + (y2 - y1)**2)
side2 = math.sqrt((x3 - x2)**2 + (y3 - y2)**2)
side3 = math.sqrt((x1 - x3)**2 + (y1 - y3)**2)

semiperimetr = (side1 + side2 + side3) / 2

area = math.sqrt(semiperimetr * (semiperimetr - side1) * (semiperimetr - side2) * (semiperimetr - side3) )

print("Площадь треугольника: ", area)