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




int main(){

int n;
cin >> n;
string s;
cin >> s;
string s1 = "";
s1 += s[0];
int ans = 0;
for (int i = 0; i < n; i++){
    if (s[i] == '(' && s[i+1] == ')'){
        ans += 1;
    }
    if (s[i] == ')' && s[i+1] == ')'){
        ans += 1;
    }

}

cout << ans;





/*   for (int i = 0; i < n; i++){
 if (s[i] == '('){
        cnt1+=1;
    }
    if (s[i] == ')'){
        cnt2+=1;
    }
}

if (cnt1>cnt2){
        cout << cnt2;
    }
if (cnt1<cnt2){
        cout << cnt1;
    }
if (cnt1 == cnt2){
    cout << cnt1;
}*/

}