#include <iostream>
using namespace std;

int main()
{
    int n;
    string s;
    cin >> n >> s;
    for (int i = 0; i < n; i++)
    {
        if (s[i] == '#')
        {
            s = s.substr(i);
            n = s.size();
            break;
        }
    }
    int c = 0;
    int ans = n;
    for (int i = 0; i < n; i++)
    {
        if (s[i] == '#')
        {
            c++;
        }
        ans = max(ans, n + c * 2 - i - 2);
    }
    cout << ans << endl;
}