#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 n;
string s;

int solve() {
	int left = n - 1;
	for (int i = 0; i < n; i++) {
		if (s[i] == '#') {
			left = i;
			break;
		}
	}

	int ans = 0;
	for (int i = left; i < n; i++) {
		if (s[i] == '#') {
			continue;
		}

		ans++;
	}

	return ans;
}

int solve2() {
	int ans = 0;
	for (auto c : s) {
		if (c == '#') {
			ans++;
		}
	}

	return ans;
}

int solve3() {
	int ans = 0;
	for (auto c : s) {
		if (c == '.') {
			ans++;
		}
	}

	return ans;
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	// #.
	// ↓
	// .#

	cin >> n >> s;

	
	int ans = min(solve(), solve2(), solve3());
	cout << ans << endl;
	return 0;
}
