#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <queue>
#include <algorithm>
#include <numeric>
#include <deque>
#include <complex>
#include <cassert>

using namespace std;
using ll = long long;

int main(){

    int N, ans=0, m;
    string S;
    cin >> N >> S;

    for (int i=0; i<N; i++){
        if (S[i] == '#'){
            m = i;
            break;
        }
    }

    for (int i=N-1; i>=m+1; i--){
        if (S[i] == '#') ans++;
        else ans = max(0, ans-1);
    }

    cout << ans+N-m << endl;

    return 0;
}