921. Minimum Add to Make Parentheses Valid - LeetCode Solution

class Solution:
    def minAddToMakeValid(self, S: str) -> int:
        a = []

        count = 0

        for i in range(len(S)):
            if(S[i] == "("):
                a.append(S[i])
            else:
                if(len(a) == 0):
                    count+=1
                else:
                    a.pop()

        count+= len(a)
        
        return count