my code of python

```
class Solution:
# @param tokens, a list of string
# @return an integer
def evalRPN(self, List):
if len(List) < 3:
return int(List[0])
operate = ['+','-','*','/']
x = 0
y = 0
number = []
for a in List:
if a in operate:
y = number.pop()
x= number.pop()
number.append(self.__oprate(a,x,y))
else:
number.append(int(a))
return number[0]
def __oprate(self,op,x,y):
if op == '+':
return x + y
elif op == '-':
return x - y
elif op == '*':
return x * y
elif op == '/':
if y == 0:
return 0
else:
return int(x / y)
else:
return 0
```

Submission Result: Wrong Answer

Input: ["10","6","9","3","+","-11","*","/","*","17","+","5","+"]

Output: 12

Expected: 22

But in my computer output is 22,why?

somebody can review my code and tell me why?