text: x=list(input().split(","))
  y=[]
  count=0
  for j in x:
      y.append(int(j))
      if int(j)<0:
          count+=1
  res=0
  for i in range(len(y)):
      res=res+ abs(y[i])*pow(10,len(y)-i-1)
  if count%2==0:
      print(res)
  else:
      print (res* -1)