#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Edge = pair<int, int>;
using Graph = vector<vector<Edge>>;
const ll MOD = 1000000007;
const ll nmax = 8;
const ll INF = 1e9;
bool graph[nmax][nmax];
vector<vector<ll>> dist = vector<vector<ll>>(nmax, vector<ll>(nmax, INF));
void warshall_floyd(ll n) {
  for (size_t i = 0; i < n; i++) {
    for (size_t j = 0; j < n; j++) {
      for (size_t k = 0; k < n; k++) {
        dist[j][k] = min(dist[j][k], dist[j][i] + dist[i][k]);
      }
    }
  }
}
class UnionFind {
 public:
  vector<ll> Parent;
  UnionFind(ll N) { Parent = vector<ll>(N, -1); }
  ll find(ll A) {
    if (Parent[A] < 0) return A;
    return Parent[A] = find(Parent[A]);
  }
  ll size(ll A) { return -Parent[find(A)]; }
  bool Union(ll A, ll B) {
    A = find(A);
    B = find(B);
    if (A == B) {
      return false;
    }
    if (size(A) < size(B)) swap(A, B);
    Parent[A] += Parent[B];
    Parent[B] = A;
    return true;
  }
};
ll gcd(ll a, ll b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
ll lcm(ll a, ll b) {
  ll g = gcd(a, b);
  return a / g * b;
}
ll mulMod(ll a, ll b) { return (((a % MOD) * (b % MOD)) % MOD); }
ll powMod(ll a, ll p) {
  if (p == 0) {
    return 1;
  } else if (p % 2 == 0) {
    ll half = powMod(a, p / 2);
    return mulMod(half, half);
  } else {
    return mulMod(powMod(a, p - 1), a);
  }
}
ll ceil(ll a, ll b) { return (a + b - 1) / b; }
void solve(long long N, std::string S) {
  int cnt_white = 0;
  for (int i = 0; i < N; i++) {
    if (S[i] == '.') cnt_white++;
  }
  ll ans = INF;
  ll black = 0;
  ll white = 0;
  for (int i = 0; i < N; i++) {
    if (S[i] == '#') {
      black++;
    } else {
      white++;
    }
    ans = min(ans, black + cnt_white - white);
  }
  if (ans == INF) {
    ans = 0;
  }
  cout << ans << endl;
}
int main() {
  long long N;
  scanf("%lld", &N);
  std::string S;
  std::cin >> S;
  solve(N, S);
  return 0;
}
