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

int main() {
	char line[200];
	int n;
	cin >> n;
	cin >> line;
	long long val[200];
	long long next[200];
	int valPos = 0;
	int pos = 0;
	for ( ; ;) {
		if (pos == n) {
			break;
		}
		if (line[pos] == '(' && line[pos + 1] == ')') {
			val[valPos] = 1;
			valPos++;
			pos += 2;
			continue;
		}
		if (line[pos] == '(') {
			val[valPos] = -1;
		}
		if (line[pos] == ')') {
			val[valPos] = 0;
		}
		valPos++;
		pos++;
	}
	for ( ; ;) {
		if (valPos == 1) {
			break;
		}
		int nextPos = 0;
		int currentPos = 0;
		for ( ; ;) {
			if (currentPos >= valPos) {
				break;
			}
			if (val[currentPos] <= 0) {
				next[nextPos] = val[currentPos];
				nextPos++;
				currentPos++;
				continue;
			}
			long long tmp = 1;
			while (currentPos < valPos && val[currentPos] > 0) {
				tmp *= val[currentPos];
				currentPos++;
			}
			next[nextPos] = tmp;
			nextPos++;
		}
		memcpy(val, next, nextPos * sizeof(long long));
		valPos = nextPos;
		
		nextPos = 0;
		currentPos = 0;
		for ( ; ;) {
			if (currentPos == valPos) {
				break;
			}
			if (currentPos > 0 && currentPos < valPos && val[currentPos] > 0 && val[currentPos - 1] == -1 && val[currentPos + 1] == 0) {
				nextPos--;
				next[nextPos] = val[currentPos] + 1;
				currentPos += 2;
				nextPos++;
				continue;
			}
			next[nextPos] = val[currentPos];
			nextPos++;
			currentPos++;
		}
		memcpy(val, next, nextPos * sizeof(long long));
		valPos = nextPos;
	}
	cout << val[0] << endl;
	return 0;
}