from decimal import Decimal
A, B, C = map(int,input().split())

#s = (A + B + C) / 2
#面積S = √s * (s - a) * (s - b) * (s - c) 

s = (A + B + C)/2
S = (s * (s - A) * (s - B) * (s - C))

ans = 2 * (S ** 0.5)
ans = ans / (A + B + C)
print(ans)