编辑代码

# coding:utf-8
#JSRUN引擎2.0,支持多达30种语言在线运行,全仿真在线交互输入输出。 
import functools
import sys
 
  
# 处理输入
params = [x for x in input().split(" ")]
 
scores = []
 
flag = False
for i in range(len(params)):
    if (params[i] == "+") :
        if len(scores)<2:
            print(-1)
            flag = True
            break
        scores.append(scores[len(scores)-2] + scores[len(scores)-1])
    elif (params[i] == "D") :
        if len(scores)<1:
            print(-1)
            flag = True
            break
        scores.append(2*scores[len(scores)-1])
    elif (params[i] == "C"):
        if len(scores)<1:
            print(-1)
            flag = True
            break
        scores.pop()
    else:
        scores.append(int(params[i]))
 
if not flag:
    print(sum(scores))