#include <iostream>
#include <string>
#include <list>
using namespace std;

int main()
{
    int N, cookies = 0;
    bool flag = true;
    string S;
    char S2[N];
    cin >> N;
    cin >> S;

    for(int i = 1; i < N; i++)
    {
        if (S[i] == ')' && S[i - 1] == '(' || S[i] == ')' && S[i - 1] == ')')
            cookies += 1;
    }

    cout << cookies;

    return 0;
}