## Area of a triangle
"""
S = (a + b + c) / 2
area = sqrt(s(s-a)(s-b)(s-c))
"""

a = float(input("Enter a: "))
b = float(input("Enter b: "))
c = float(input("Enter c: "))

#calculate the semi-perimeter
s = (a + b + c) / 2
#calculate the area
area = (s*(s-a)*(s-b)*(s-c)) ** 0.5
print("the area of triangle is %0.2f" %area )