#include <iostream>
#include <cassert>
#include <vector>
using namespace std;
constexpr long long M = 1e9+7, OPEN=-1, CLOSE=-2;
using I = vector<long long>::iterator;
long long dfs(I begin, I end, bool op){
	assert(*begin == OPEN and *end == CLOSE);
	long long v = op?0:1;
	for(++begin;begin!=end; ++begin){
		if(*begin == CLOSE) assert(false);
		long long x;
		if(*begin == OPEN){
			auto s = begin;
			int cnt = 1;
			while(cnt){
			   	++begin;
			   	if(*begin == OPEN) ++cnt;
				if(*begin == CLOSE) --cnt;
			}
			x = dfs(s, begin, !op);
		} else {
			x = *begin;
		}
		if(op) v = (v+x)%M; else v = v*x%M;
	}
	return v;
}
int main(){
	int n; cin >> n;
	vector<long long> l;
	l.push_back(OPEN);
	for(int i = 0; i < n; ++i){
		string s; cin >> s;
		if(s == "(") l.push_back(OPEN);
		else if(s == ")") l.push_back(CLOSE);
		else l.push_back(stoll(s));
	}
	l.push_back(CLOSE);
	cout << dfs(begin(l), prev(end(l)), true) << endl;
}