import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################

a,b, c = na()
d = (a + b + c)  / 2
s = (d * (d - a) * (d - b) * (d- c) ) ** 0.5
print(s * 2 / (a + b + c))