#include <iostream>
#include <string>
#include <climits>

using namespace std;

int N;
string S;
int preW[200005];
int preB[200005];
int ans=INT_MAX;

int main()
{
	cin >> N >> S;
	for (int i=1; i<=N; i++)
	{
		preW[i]=preW[i-1]+(S[i-1]=='.'?1:0);
		preB[i]=preB[i-1]+(S[i-1]=='#'?1:0);
	}
	for (int i=0; i<=N; i++) ans=min(ans,preB[i]+preW[N]-preW[i]);
	cout << ans;
	return 0;
}