using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(int n) => Enumerable.Repeat(0, n).Select(_ => NList).ToArray();
    static void Main()
    {
        var n = NN;
        var s = ReadLine();
        WriteLine(Tunnel(s));
    }
    static int Tunnel(string _s)
    {
        var s = _s.ToCharArray();
        Array.Reverse(s);
        var late = 0;
        var res = 0;
        for (var i = 0; i < s.Length; ++i)
        {
            if (i > 0)
            {
                if (s[i - 1] == '#' && s[i] == '#') ++late;
                if (s[i - 1] == '.' && s[i] == '.') if (late > 0) --late;
            }
            if (s[i] == '#')
            {
                res = i + 1 + late;
            }
        }
        return (res);
    }
}