万事俱全，只欠提交成功

依旧提交失败😒😒

#include <iostream>
#include <string>
using namespace std;

int main() {
    string s;
    cin >> s;
    int balance = 0;
    int max_length = 0;

    for (char c : s) {
        if (c == '(') {
            balance++;
        } else if (balance > 0) {
            balance--;
            max_length += 2;
        }
    }
    cout << max_length << endl;
    return 0;
}