#include <iostream>
#include <string>
#include <vector>
#include <sstream>

using namespace std;

vector<uint> indexOf(string hay, string needle, uint len)
{
    vector<uint> positions;
    uint needleLen = needle.length();
    for (uint i = 0; i <= len - needleLen; i++)
    {
        bool match = true;
        for (uint j = 0; j < needleLen; j++)
        {
            if (needle[j] != hay[i+j])
            {
                match = false;
                break;
            }
        }
        if (match)
            positions.push_back(i);
    }
    return positions;
}

void findReplace(string& ss, string find, string replace, uint len)
{
    auto positions = indexOf(ss, find, len);
    uint rlen = replace.length(), flen = find.length();
    int difflen = rlen-flen; //difflen = how many characters do we gain/lose upon insertion
    //Resize ss to fit replacements
    int offset = 0;
    uint start = 0;
    if (difflen < 0)
    {
        for (uint i = 0; i < positions.size(); i++)
        {
            for (uint j = start; j < positions[i]; j++)
            {
                ss[j + offset] = ss[j];
            }
            for (uint j = 0; j < rlen; j++)
            {
                ss[positions[i] + j + offset] = replace[j];
            }
            start = positions[i] + flen;
            offset += difflen;
        }
        for (uint i = start; i < len+offset; i++)
        {
            ss[i] = ss[i-offset];
        }
    }
    ss.resize(len + offset);
}

string resExp(string in)
{
    stringstream ss("");
    char lastChar = 0;
    for (uint i = 0; i < in.length(); i++)
    {
        switch (lastChar)
        {
            case ')':
                if (in[i] == '(')
                    ss.put('+');
                if (in[i] == ')') {
                    ss.put('+');
                    ss.put('1');
                }
                break;
            case '(':
                if (in[i] == ')')
                    ss.put('1');
                break;
        }
        lastChar = in[i];
    }
    return ss.str();
}

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

    string reString = resExp(s);


    auto plusPos = indexOf(reString, "+", reString.length());
    vector<string> strInt(plusPos.size()+1, "");
    uint i, lastpos=0;
    uint res = indexOf(reString, "1", reString.length()).size();
    /*
    for (i = 0; i < plusPos.size(); i++)
    {
        strInt[i] = reString.substr(lastpos, plusPos[i] - lastpos);
        lastpos = plusPos[i]+1;
    }
    strInt[i] = reString.substr(lastpos, reString.length() - lastpos);
    uint res = 0;
    for (uint i = 0; i < strInt.size(); i++)
    {
        res += stoul(strInt[i]);
    }*/
    cout << res << endl;
    return 0;
}