class Solution:
    def calculate(self, s: str) -> int:
        stack = []
        num = 0
        sign = 1
        result = 0

        for char in s:
            if char.isdigit():
                num = num * 10 + int(char)
            elif char == "+":
                result += sign * num
                num = 0
                sign = 1
            elif char == "-":
                result += sign * num
                num = 0
                sign = -1
            elif char == "(":
                stack.append(result)
                stack.append(sign)
                result = 0
                sign = 1
            elif char == ")":
                result += sign * num
                num = 0
                result *= stack.pop()  # Pop the sign.
                result += stack.pop()  # Pop the preceding result.

        result += sign * num
        return result


# Example usage:
solution = Solution()
s = "(1+(4+5+2)-3)+(6+8)"
result = solution.calculate(s)
print(result)  # Output: 23