#include<iostream>

using namespace std;

int main()
{
    string s;
    cin >> s;

    int bal = 0, k = 0, ans;
    for(int i = 0; i < s.size(); i++)
    {
        if (s[i] == '(') bal++;
        else bal--;
        if (bal+k < 0)
        {
            ans++;
            k++;
        }
    }
    cout << ans + bal;
}