#include <fstream>
#include <stack>

using std::ifstream;
using std::ofstream;
using std::stack;
using std::max;

stack <bool> S;
int main (void) {
    ifstream fin ("paranteze2.in");
    ofstream fout ("paranteze2.out");
    char x;
    int _max=0;
    while (fin >> x)
        if (x=='(') {
            S.push(1);
            _max=max(_max, (int)S.size());
        }
        else
            S.pop();
    fout << _max;
    return 0;
}