#include<iostream>
using namespace std;
int N;
string S;
int main()
{
	cin>>N>>S;
	int c=-1,l=0;
	for(int i=N;i--;)if(S[i]=='#')
	{
		c+=2;
		l=min(l,c-(N-i));
	}
	cout<<c-l<<endl;
}