include<bits/stdc++.h>

using namespace std; long long n,i,a[1009],b[1009],d,j,k,dem,s1,s2; string s; int main (){ cin>>n; cin>>s; i=0; while (i<s.size()){ while (s[i]!='#'&&i<s.size()) i++; j=i; while (s[i]!='.'&&i<s.size()) i++; if (i-j>0&&s[i]=='.'){ d++; a[d]=i-j; } } i=s.size()-1; while (i>=0){ while(s[i]!='.'&&i>=0) i--; j=i; while (s[i]!='#'&&i>=0) i--; if (j-i>0 && s[i]=='#'){ k++; b[k]=j-i; } } for (i=1;i<=d;i++) s1=s1+a[i]; for (i=1;i<=k;i++) s2=s2+b[i]; cout<<min(s1,s2); }