#include <bits/stdc++.h>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
const double PI = acos(-1);
template <class T>
constexpr T INF() {
  return ::std::numeric_limits<T>::max();
}
template <class T>
constexpr T HINF() {
  return INF<T>() / 2;
}
template <typename T_char>
T_char TL(T_char cX) {
  return tolower(cX);
};
template <typename T_char>
T_char TU(T_char cX) {
  return toupper(cX);
};
const int vy[] = {-1, -1, -1, 0, 1, 1, 1, 0},
          vx[] = {-1, 0, 1, 1, 1, 0, -1, -1};
const int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0};
int popcnt(unsigned long long n) {
  int cnt = 0;
  for (int i = 0; i < 64; i++)
    if ((n >> i) & 1) cnt++;
  return cnt;
}
int d_sum(LL n) {
  int ret = 0;
  while (n > 0) {
    ret += n % 10;
    n /= 10;
  }
  return ret;
}
int d_cnt(LL n) {
  int ret = 0;
  while (n > 0) {
    ret++;
    n /= 10;
  }
  return ret;
}
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;
};
int n;
string s;
int wcnt[202020], bcnt[101010];
int main() {
  cin >> n;
  cin >> s;
  for (LL i = (0); i < (n); i++) {
    if (i) {
      wcnt[i] = wcnt[i - 1];
    }
    if (s[i] == '.') wcnt[i]++;
  }
  wcnt[n] = wcnt[n - 1];
  for (int i = n - 1; i >= 0; i--) {
    bcnt[i] = bcnt[i + 1];
    if (s[i] == '#') bcnt[i]++;
  }
  int ans = n - bcnt[0];
  for (int i = 1; i <= n; i++) {
    ans = min(ans, (i - wcnt[i - 1]) + (n - i - bcnt[i]));
  }
  cout << ans << endl;
}
