#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;
int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};
constexpr ll mod = 1e9 + 7;
constexpr ll inf = INT32_MAX / 2;
constexpr ll INF = LLONG_MAX / 2;
constexpr long double eps = DBL_EPSILON;
constexpr long double pi = 3.141592653589793238462643383279;
template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
ll fact(int i) {
  if (i == 0) return 1;
  return (fact(i - 1)) * i;
}
ll gcd(ll a, ll b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
ll lcm(ll a, ll b) { return a * b / gcd(a, b); }
int keta(ll n) {
  if (n == 0) return 1;
  int count = 0;
  while (n != 0) {
    n /= 10;
    count++;
  }
  return count;
}
ll ketasum(ll n) {
  ll sum = 0;
  while (n != 0) {
    sum += n % 10;
    n /= 10;
  }
  return sum;
}
int main() {
  int n;
  string s;
  cin >> n >> s;
  int white = 0;
  int count = 0;
  for (int i = 0; i < (int)(n); i++)
    if (s[i] == '.') white++;
  for (int i = (int)(n - 1); i >= 0; i--) {
    if (s[i] == '.') {
      if (s[i - 1] == '#') {
        count++;
        s[i - 1] = '.';
      }
    }
  }
  cout << min(white, count) << endl;
  return 0;
}
