#include <iostream>
#include <string>

std::string input;
int index = 0;

long long rek(){
    long long sum = 0;
    while (true){
        std::string lulz = {input[index], input[index + 1]};
        index++;
        if (lulz == "((") sum += rek();
        else if (lulz == "))") return sum + 1;
        else if (lulz == "()") return 1;
        else if (lulz == ")(") sum *= rek();
        else std::cout << "WTFFFFFF " << lulz;
    }

}

int main(){
    std::ios_base::sync_with_stdio(false);
    std::cin >> index >> input;
    index = 0;

    std::cout << rek() << std::endl;

}