#include <algorithm>
#include <bitset>
// #include <boost/dynamic_bitset.hpp>
#include <cfloat>
#include <cmath>
#include <ctime>
#include <chrono>
#include <deque>
#include <iomanip>
#include <iostream>
#include <limits>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <typeindex>
#include <typeinfo>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#define DEBUG(x) cout << #x << ": " << x << endl
#define INFILE() freopen("input.txt", "r", stdin)
#define REP(i, a, b) for (int i = (a); i < (b); i++)
#define REPC(i, a) REP(i, 0, a)
#define RREP(i, a, b) for (int i = (a); i >= (b); i--)
#define RREPC(i, a) RREP(i, a, 0)
#define ALL(s) begin(s), end(s)
#define RALL(s) rbegin(s), rend(s)

using namespace std;

using ll = long long;
using ull = unsigned long long;
using i_i = pair<int, int>;
using ll_i = pair<ll, int>;
using i_ll = pair<int, ll>;
using d_i = pair<double, int>;
using ll_ll = pair<ll, ll>;
using d_d = pair<double, double>;

static constexpr ll LL_MOD = 1000000009;
static constexpr ll LL2_MOD = 1000000007;
static constexpr double EPS = numeric_limits<double>::epsilon();
static constexpr double PI = 3.14159265358979323846264338327950288;

static map<type_index, const char *const> scanType = { { typeid(int), "%d" },
{ typeid(ll), "%lld" },
{ typeid(double), "%lf" },
{ typeid(char), "%c" } };

template <class T> static void scan(vector<T> &v);
static void scan(vector<string> &v, bool isWord = true);
// static boost::dynamic_bitset<> scan(char trueValue = 'o');

int main(int argc, char *argv[]) {
	 //INFILE();

	 ll l;
	 cin >> l;
	 string s;
	 cin >> s;
	 vector<ll> v(l);

	 ll count = 0;
	 for (int i = 0; i < l; i++) {
		 v[i] = count;
		 
		 if (s[i] == '#') count++;
	 }

	 if (count == 0) {
		 cout << 0 << endl;
		 return 0;
	}

	 count = 0;
	 ll minCount = 999999999;
	 for (int i = l - 1; i >= 0; i--) {
		 if (s[i] == '.') count++;

		 v[i] += count;
		 if (v[i] < minCount) minCount = v[i];
	 }

	 if (count == 0) {
		 cout << 0 << endl;
		 return;
	}

	 cout << minCount << endl;
	return 0;
}

template <class T> static void scan(vector<T> &v) {
	auto tFormat = scanType[typeid(T)];
	for (T &n : v) {
		scanf(tFormat, &n);
	}
}

static void scan(vector<string> &v, bool isWord) {
	if (isWord) {
		for (auto &n : v) {
			cin >> n;
		}
		return;
	}

	int i = 0, size = static_cast<int>(v.size());
	string s;
	getline(cin, s);

	if (s.size() != 0) {
		i++;
		v[0] = s;
	}

	for (; i < size; ++i) {
		getline(cin, v[i]);
	}
}

//static boost::dynamic_bitset<> scan(char trueValue) {
//	string s;
//	getline(cin, s);
//
//	if (s.size() == 0) {
//		getline(cin, s);
//	}
//
//	for_each(begin(s), end(s),
//		[trueValue](char &c) { c = (c == trueValue) ? '1' : '0'; });
//	return boost::dynamic_bitset<>(string(rbegin(s), rend(s)));
//}
