# put your python code here
import math

a = int(input())
b = int(input())
c = int(input())

p = (a + b + c) / 2
d = p * (p - a) * (p - b) * (p - c)
s = math.sqrt(d)
print(s)

059e44a2aed54a0550180d234f0e8847dc344a93
<mask token>

<mask token>
print(s)

<mask token>
a = int(input())
b = int(input())
c = int(input())
p = (a + b + c) / 2
d = p * (p - a) * (p - b) * (p - c)
s = math.sqrt(d)
print(s)

import math
a = int(input())
b = int(input())
c = int(input())
p = (a + b + c) / 2
d = p * (p - a) * (p - b) * (p - c)
s = math.sqrt(d)
print(s)

# put your python code here
import math

a = int(input())
b = int(input())
c = int(input())

p = (a + b + c) / 2
d = p * (p - a) * (p - b) * (p - c)
s = math.sqrt(d)
print(s)
