#include <stdio.h>

int main()
{
	int N;
	char S[200001];
	scanf("%d", &N);
	scanf("%s", S);
	
	int i, k, ans = 0;
	for (i = 0, k = 1; i < N; i++) {
		if (k == 0) {
			if (S[i] == '(') k = 2;
			else if (S[i] == '?') {
				if (S[i+1] == '?' || S[i+1] == ')') k = 2;
			}
		} else {
			if (S[i] == '(') k++;
			else {
				k--;
				if (k == 0) ans++;
			}
		}
	}
	if (k == 1) ans++;
	printf("%d\n", ans);
	fflush(stdout);
	return 0;
}