HZNUOJ


Problem_ID: B
Result: Accepted
Time: 110ms
Memory: 24316kB
Author: 2018212212118
In contest: 1273


while 1:
  try:  
    a,b,c=map(int,input().split())
    if a+b<=c or a+c<=b or b+c<=a:
      print("invalid triangle")
    else:
      p=(a+b+c)/2
      s=(p*(p-a)*(p-b)*(p-c))**0.5
      print("%.2f"%s)
  except:
      break
  pass