#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
const double PI = 3.1415926535897932384626433832795;
const int dx[] = {0, 1, 0, -1};
const int dy[] = {-1, 0, 1, 0};
int gcd(int x, int y) { return y ? gcd(y, x % y) : abs(x); }
ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : abs(x); }
int lcm(int x, int y) { return x / gcd(x, y) * y; }
ll lcm(ll x, ll y) { return x / gcd(x, y) * y; }
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  string s;
  cin >> n >> s;
  int left = n - 1;
  for (int i = 0; i < n; i++) {
    if (s[i] == '#') {
      left = i;
      break;
    }
  }
  int ans = 0;
  for (int i = left + 1; i < n; i++) {
    if (s[i] == '#') {
      continue;
    }
    ans++;
  }
  cout << ans << endl;
  return 0;
}
