#include <bits/stdc++.h>
using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;
#define int ll

typedef pair<int, int> pii;
typedef pair<pii, pii> piii;
typedef vector<piii> vpii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector< vi > vvi;
typedef vector< vvi > vvvi;
typedef vector<pii> vpi;
typedef vector<short> vs;
typedef vector<vs> vvs;
typedef vector<vvs> vvvs;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
typedef vector<ld> vld;
typedef vector<vld> vvld;
typedef vector<vvld> vvvld;
typedef vector<string> vst;
typedef vector<vst> vvst;
typedef pair<ld, ld> pld;
typedef complex<double> base;

#define inmin(a, b) a = min(a, (b))
#define inmax(a, b) a = max(a, (b))
#define mp(a, b) make_pair(a, (b))
#define ALL(a) a.begin(),a.end()
#define RALL(a) a.rbegin(),a.rend()
#define sqr(x) ((x) * (x))
#define fori(i, n) for(int i = 0; i < int(n); ++i)
#define SZ(a) ((int)((a).size()))
#define triple(T) tuple<T, T, T>
#define quad(T) tuple<T, T, T, T>
#define watch(x) cout << (#x) << " = " << x << endl;
#ifdef MAX_HOME
#define cerr cout
#else
#define cerr if (false) cerr
#endif


void err(istream_iterator<string> it) {}
template<typename T, typename... Args>
void err(istream_iterator<string> it, T a, Args... args) {
    cerr << *it << " = " << a << endl;
    err(++it, args...);
}

const double PI = 2 * acos(0.0);

const string DIGITS = "0123456789";
const string ALPH = "abcdefghijklmnopqrstuvwxyz";


istream &operator >> (istream &in, pii &a)
{
    in >> a.first >> a.second;
    return in;
}


ostream &operator << (ostream &out, pii &a)
{
    out << a.first << ' ' << a.second;
    return out;
}


template <class T0, class T1>
inline ostream & operator << (ostream &out, pair<T0, T1> &a) {
    return out << "{" << a.first << ", " << a.second << "}";
}

template <class T0, class T1, class T2>
inline ostream & operator << (ostream &out, tuple<T0, T1, T2> &a) {
    return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a) << "}";
}

template <class T0, class T1, class T2, class T3>
inline ostream & operator << (ostream &out, tuple<T0, T1, T2, T3> &a) {
    return out << "{" << get<0>(a) << ", " << get<1>(a) <<
               ", " << get<2>(a) << ", " <<  get<3>(a) << "}";
}

template<class T>
inline ostream & operator << (ostream &out, vector<T> &a) {
    out << "[";
    fori (i, a.size())
        out << a[i] << vector<string>{", ", "]  "}[i + 1 == a.size()];
    return out;
}


void smain();

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

#ifdef ART_HOME
    freopen("input.txt", "r", stdin);
    clock_t start = clock();
#endif
    cout << setprecision(12) << fixed;
    smain();
#ifdef ART_HOME
    cout << "\n\n\n\nTOTAL EXECUTION TIME: " << float( clock () - start ) /  CLOCKS_PER_SEC << endl;
#endif
}


const int N = 1 << 10, M = 1e9 + 7;

vvi mat;


int MOD(int v)
{
    return (v % M + M) % M;
}


int bin_pow(int v, int k)
{
    int res = 1;
    while (k)
    {
        if (k & 1)
            res = MOD(res * v);

        v = MOD(v * v);
        k >>= 1;
    }

    return res;
}


int inv(int v)
{
    return bin_pow(v, M - 2);
}


vvi mult(vvi a, vvi b)
{
    vvi c(SZ(a));
    for (int i = 0; i < SZ(a); ++i)
        c[i].resize(SZ(a));

    int n = SZ(a);
    for (int i = 0; i < n; ++i)
        for (int j = 0; j < n; ++j)
            for (int k = 0; k < n; ++k)
                c[i][j] = MOD(c[i][j] + a[i][k] * b[k][j]);

    return c;
}


vvi bin_pow_mat(vvi chal, int k)
{
    vvi res(SZ(chal));
    for (int i = 0; i < SZ(chal); ++i)
        res[i].resize(SZ(chal));

    for (int i = 0; i < SZ(chal); ++i)
        res[i][i] = 1;

    while (k)
    {
        if (k & 1)
            res = mult(res, chal);

        k >>= 1;
        chal = mult(chal, chal);
    }

    return res;
}


void smain()
{
    int n;
    cin >> n;

    string s;
    cin >> s;

    vi cnt(n);
    for (int i = 0; i < n; ++i)
        cnt[i] = int(s[i] == '#');

    for (int i = 1; i < n; ++i)
        cnt[i] += cnt[i - 1];

    int ans = min(n - cnt.back(), cnt.back());
    for (int i = 1; i < n; ++i)
        ans = min(ans, cnt[i - 1] + (n - i - (cnt.back() - cnt[i - 1])));

    cout << ans;
}


Measured memory_bytes: 2196