#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;
int main(){
  int n;
  string s;
  cin >> n >> s;
  int cntb=0,cntw=0;
  vector<int> b(n+2,0),w(n+2,0);
  for(int i=0;i<n;i++){
    if(s[i]=='#') cntb++;
    if(s[n-1-i]=='.') cntw++;
    b[i+1]=cntb;
    w[n-i]=cntw;
  }
  int ans=b[0]+w[1];
  for(int i=1;i<n+2;i++){
    ans=min(ans,b[i-1]+w[i]);
  }
  cout << ans << endl;
}