#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef pair<ll, ll> p_ll;

template<class T>
void debug(T itr1, T itr2) { auto now = itr1; while(now<itr2) { cout << *now << " "; now++; } cout << endl; }
#define repr(i,from,to) for (ll i=(ll)from; i<(ll)to; i++)
#define all(vec) vec.begin(), vec.end()
#define rep(i,N) repr(i,0,N)
#define per(i,N) for (int i=(int)N-1; i>=0; i--)

const ll MOD = pow(10,9)+7;
const ll LLINF = pow(2,61)-1;
const int INF = pow(2,30)-1;

vector<ll> fac;
void c_fac(int x=pow(10,6)+10) { fac.resize(x,true); rep(i,x) fac[i] = i ? (fac[i-1]*i)%MOD : 1; }
ll inv(ll a, ll m=MOD) { ll b = m, x = 1, y = 0; while (b!=0) { int d = a/b; a -= b*d; swap(a,b); x -= y*d; swap(x,y); } return (x+m)%m; }
ll nck(ll n, ll k) { return fac[n]*inv(fac[k]*fac[n-k]%MOD)%MOD; }
ll gcd(ll a, ll b) { if (a<b) swap(a,b); return b==0 ? a : gcd(b, a%b); }
ll lcm(ll a, ll b) { return a/gcd(a,b)*b; }


int main() {
  ll N; cin >> N; N--;
  string S; cin >> S;
  ll len = S.size();
  ll lf = 0; while (lf<len&&S[lf]=='.') lf++; lf = min(lf,N);
  ll rf = len-1; while (rf>=0&&S[rf]=='.') rf--; rf = max(rf,N);

  ll result = LLINF;
  string sl = S, sr = S;
  // 左端からせめてく
  ll resl = N-lf; repr(i,lf,N) sl[i] = sl[i]=='.' ? '#' : '.';
  repr(i,lf,rf) {
    if (sl[i]=='.') { resl += 1; sl[i+1] = sl[i+1]=='.' ? '#' : '.';  }
    else { resl += i+1==rf ? 2 : 3; sl[i] = '.'; }
  }

  // 右端からせめてく
  ll resr = rf-N; repr(i,N+1,rf+1) sr[i] = sr[i]=='.' ? '#' : '.';
  for (ll i=rf; i>lf; i--) { 
    // cout << i << " " << sr << " " << resr << endl;
    if (sr[i]=='.') { resr += 1; sr[i-1] = sr[i-1]=='.' ? '#' : '.';  }
    else { resr += i-1==lf ? 2 : 3; sr[i] = '.'; }
  }
  
  // cout << resl << " " << resr << endl;

  result = min(resl, resr);
  if (lf==rf&&lf==N) result = 3;
  cout << result << endl;
  return 0;
}