using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

public class MainClass
{
	public const long Giri = 1000000007;
	public const long DpInf = 99999999999999;
	
	public static void Main(string[] args)
	{
		var n = Console.ReadLine().ToInt();
		var s = Console.ReadLine();
		bool all = true;
		int black = 0;
		for(int i = 0; i < n; i++)
		{
			if(s[i] == '.')
				black++;
			if(s[0] != s[i])
				all = false;
		}
		if(all)
		{
			Console.WriteLine(0);
			return;
		}
		int min = n;
		int rw = 0;
		for(int i = 0; i < n; i++)
		{
			if(s[i] == '#')
				rw++;
			else
				black--;
			min = Math.Min(min, black+rw);
		}
		Console.WriteLine(min);
	}
	
	
	static long GCD(long a, long b)
	{
		var v = new[] { a, b };
		while (v[1] != 0) { v = new[] { v[1], v[0] % v[1] }; }
		return v[0];
	}
	public static string[] Input() { return Console.ReadLine().Split(); }
}

public static class Smarter
{
	public static int ToInt(this string str) { return int.Parse(str); }
	public static long ToLong(this string str) { return long.Parse(str); }
	public static int[] ToInt(this string[] str, int offset = 0)
	{
		var r = new int[str.Length];
		for(int i = 0; i < str.Length; i++) r[i] = str[i].ToInt() + offset;
		return r;
	}
}