output_description: Print the computational result in a line.
input_description: An expression is given in a line. Two consequtive symbols (operand or
  operator) are separated by a space character.
  
  You can assume that +, - and * are given as the operator and an operand is a
  positive integer less than 106
attempt: inputEnzan = input().split()
  stack = []
  while True:
      if "-" in inputEnzan or "+" in inputEnzan or "*" in inputEnzan:
          index = 0
          while index < len(inputEnzan):
              if len(inputEnzan) == 1:
                  break
              if (
                  inputEnzan[index] == "-"
                  or inputEnzan[index] == "+"
                  or inputEnzan[index] == "*"
              ):
                  if stack != []:
                      if inputEnzan[index] == "-":
                          inputEnzan[index] = stack[0] - stack[1]
                      elif inputEnzan[index] == "+":
                          inputEnzan[index] = stack[0] + stack[1]
                      else:
                          inputEnzan[index] = stack[0] * stack[1]
                      del inputEnzan[index - 2]
                      del inputEnzan[index - 2]
                      stack.clear()
                      index -= 1
                  else:
                      index += 1
              else:
                  stack.append(int(inputEnzan[index]))
                  index += 1
      else:
          print(inputEnzan[0])
          break
  
problem_description: Input
  
  An expression is given in a line. Two consequtive symbols (operand or
  operator) are separated by a space character.
  
  You can assume that +, - and * are given as the operator and an operand is a
  positive integer less than 106
samples: [{"input": "1 2 +", "output": "3"}, {"input": "1 2 + 3 4 - *", "output": "-3"}]