class Solution(object):
def calPoints(self, ops):
"""
:type ops: List[str]
:rtype: int
"""
scores = []
for op in ops:
if op == "+":
scores.append(scores[-1] + scores[-2])
elif op == "D":
scores.append(scores[-1] * 2)
elif op == "C":
scores.pop()
else:
scores.append(int(op))
return sum(scores)