class Solution:
    def minInsertions(self, s: str) -> int:
        ans = 0
        left, right = 0, 0
        
        for c in s:
            if c == '(':
                if right % 2 == 1: # 需要 two consecutive ), 出現 ( 需要立即補一個變回偶數
                    ans += 1
                    right += 1
                left += 1        
            else: # ')'
                right += 1
                if left*2 < right: # add '('
                    ans += 1
                    left += 1 

        return ans + (left * 2 - right) # add ')'