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

int main(){
    int n; cin >> n;
    string s; cin >> s;
    int ans = -1001001001;
    for(int i = n-1; i >= 0; i--){
        if(s[i] == '#') ans = max(ans+2, n-i);
    }
    cout << ans << endl;
    return 0;
}