#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int N;
  string S;
  cin>>N>>S;
  vector<int> A={};
  for(int i=0;i<N;i++)if(S[i] == '#') A.push_back(i);
  N = A.size();
  int now = 0;
  for(int i=N-2;i>=0;i--){
      now = max(0ll,now-(A[i+1]-A[i]-2));
  }
  cout<<S.size()+now-A[0]<<endl;
}