#include <bits/stdc++.h>
using namespace std;
using ll = long long;


void print_list(vector<ll> a){
	for(auto i:a){
		cout << i << ' ';
	}
	cout << '\n';
}

int main(){
    int n;
    string s;
    cin >> n >> s;
    
    vector<ll> stack;
    for(auto i:s){
		if(i == '('){
			stack.push_back(-1);
			stack.push_back(0);		
		}
		else{
			ll ansver = stack.back();
			while(stack.back() != -1){
				stack.pop_back();
				if(stack.back() != 0 && stack.back() != -1)
					ansver *= stack.back();
				//cout << ansver << '\n';
			}
			stack.pop_back();
			stack.push_back(ansver+1);
		}
		//print_list(stack);
	}
		
	cout << stack[0] << '\n';
    
    
    
    
}