#include<iostream>
#include<string>

using namespace std;

int main()
{
	int N;
	string S;

	cin >> N >> S;

	int *w,*b;

	w = new int[N+1];
	b = new int[N+1];

	int ans = N;

	int cntw = 0,cntb = 0;

	w[0] = 0;
	b[0] = 0;

	for(int i=1;i<=N;i++)
	{
		if(S[i-1] == '#')cntb++;
		if(S[i-1] == '.')cntw++;
		b[i] = cntb;
		w[i] = cntw;
	}

	for(int i=0;i<N+1;i++)
	{	
		ans = min(ans,b[i]+w[N]-w[i]);
	}

	cout << ans << endl;

	return 0;
}